Not So Special: A Critical View Of The 6.8mm SPC

Cartridges from the author's collection, left to right: 5.56x45mm Mk. 262 Mod. 1 OTM, 6.8x43mm SPC 115gr Sierra OTM, 7.62x39mm M67 FMJ.

The 5.56mm M855 round has received considerable criticism for its terminal characteristics. Detractors point out that the round fails to fragment when the striking velocity is too low – such as when fired from a very short barrel or when the bullet has slowed down thanks to its relatively unimpressive ogive shape – or when the bullet strikes the target at a very low angle of attack.

That’s one reason why it’s extremely puzzling to me that one of the most popular 5.56mm replacements – and the round many think offers the military a commercial-off-the-shelf improvement in effectiveness – offers even less in these criteria than even M855. That round is the 6.8mm Remington Special Purpose Cartridge.

The history of the 6.8mm SPC round is not the subject of this article, but some background on the cartridge’s origins can be found on page 153 of The Black Rifle II: The M16 Into The 21st Century, by Christoper R. Bartocci:

[I]n early 2002, soldiers of the 5th Special Forces Group (Abn), headed by MSG Steven Holland, received approval to initiate a Proof of Concept to develop a new capability that would increase incapacitation, lethality, and range over the existing 5.45x39mm, PRC 5.8x39mm, 7.62x39mm and 5.56x45mm NATO cartridges. This initiative was a grassroots effort aimed at providing better combat power for Special Operations Forces and soldiers of the Light Infantry, to include USMC MEU-SOC. This was the original programmatic evolution proposed for the SOPMOD Mk12 Special Purpose Rifle (SPR) system, the interim result of which was the fielding of the Mk262 77-grain ammunition, with a planned later transition to the Enhanced Rifle Cartridge (ERC) capability in a mid-bore 6.5mm, 6.8mm or 7mm caliber.

With the already proven combat success of the Mk12 SPR, the SPR concept-development team went to manufacturers in the US ammunition industry for assistance.To initiate the program, the companies involved in the development agreed to do so at their own expense, with the goal that the final product would provide US servicemen with a better capability and morale boost to combat the Global War on Terrorism (GWOT).

The assessment of the initial performance capabilities of the prototype cartridges, based on shortened commercial .30 Remington cases, was handed over to the USAMU Ammunition Section, headed by Troy Lawton. Industry involvement to consider this project at no cost to the government was championed by Sean Dwyer at Remington, who stated that Remington wanted to do their part on the Global War on Terrorism, and provide production capability for the ammunition, which would be developed and manufactured by Remington using bullets provided by Sierra and Hornady.

Several propellants were reviewed to provide improved powder performance, including Western Powder’s Ramshot, and submissions from Accuracy Arms and St. Marks Powder Company. These companies developed powders particularly for the 6.8mm Remington SPC cartridge, and will supply quantities of the chosen propellant for final assembly of ammunition by Remington. The Special Forces SPC team require that the powder used is to be manufactured in the United States, and contain an organic flash inhibitor to decrease muzzle flash in low light conditions.

Remington began the final development of the SPC cartridge in the fall of 2001, using concept wildcat brass made up by MSG Holland from shortened .30 Remington cartridge cases. AutoCAD drawings of the prototype calibers in the same cartridge case were prepared by Cris Murray of the US Army Marksmanship Unit. Remington went to work to standardize the angle of the shoulder and length of the neck. Early experimental production of ammunition began at Remington in the first quarter of 2002, and went into full production in August, 2003. During this time period several ballistic performance assessments, including accuracy and reliability- incapacitation tests, were conducted. Special Purpose Cartridges in 6.5mm, 6.8mm and 7mm calibers were reviewed to determine which bore size would best provide the capability needed by soldiers in combat. Once all the performance data were compiled the team briefed the Commander on the results, and recommended that the 6.8mm provided the best overall terminal, reliability and accuracy performance out to 450 meters. This recommendation was approved. The 6.8x43mm Remington SPC Terminal Performance results were independently confirmed by the Federal Bureau of Investigation’s Firearms Training Unit as well as by USNR/Stanford University.

It’s worth examining the dimensions of 6.8mm round itself in detail. The cartridge case is based on the rimless .30 Remington, and uses the same extractor groove and rim dimensions, with a rim diameter of .422″ or approximately 10.7mm. It uses the same case taper and shoulder angle as the 5.56mm rifle cartridge, the beta angles of those being 0.5 and 23 degrees, respectively. The round has a maximum case length of 1.6864″, or 42.83mm. Its overall length is the same as 5.56mm, at 2.26″/57.4mm, though some magazines are advertised as offering overall lengths as long as 2.315″/58.8mm, and the purpose-built Six8 rifle from LWRC, which uses proprietary magazines, offers an overall length of 2.32″/58.9mm. The cartridge has a case capacity of between 34.8 and 36.9 grs H2O (2.255-2.391 ccs), 14-21% more than the 5.56x45mm. It uses standard .277″ diameter projectiles, although it is limited in its selection of those by the overall length. In general, though the projectile diameter is the same, the 6.8mm Remington requires totally new projectiles versus existing .270 caliber rounds.

2015-03-26 22_58_08-www.saami.org_pubresources_cc_drawings_Rifle_6_8mm Remington SPC.pdf

The SAAMI cartridge drawing for the 6.8mm Remington Special Purpose Cartridge. Note the tolerances shown in the image after “-” signs; they will not be discussed in this article. Image source:


It is very curious to me that a round that was designed with an accurized designated marksman’s rifle in mind also features such a short ogive and low muzzle velocity. Typically, medium/long range precision weapons platforms place a premium on both the ballistic coefficient and velocity of the projectile, seeking to obtain as laser-like a trajectory and as high a retention of energy as possible. The 6.8mm SPC runs directly counter to this.

The ogive of a bullet is the curved portion of the projectile that is exposed outside the case. The ideal bullet shape includes as long a bullet ogive as possible, while keeping the shape as close to that of a Sears-Haack body as possible. Increasing the ogive length either increases the cartridge overall length or necessitates a decrease in case length (reducing its capacity, unless the case head diameter is increased). In terms of cartridge design within a given OAL, longer ogives come at the price of less case capacity and therefore lower muzzle velocity, but in general accepting this comes with the benefit of better velocity retention over distances beyond about a hundred meters.

In light of this, the 6.8mm SPC’s maximum ogive length is the first curiosity of the cartridge’s design. With only 2.07 calibers available space for the ogive, the maximum ogive length for the 6.8 SPC is less even than that of the 5.56x45mm or 7.62x39mm cartridges. This is very short for a rifle cartridge designed for maximum performance out to 450 meters, and limits the form factor of compatible secant-ogive projectiles to above 1.15 i7 (lower form factors yield higher ballistic coefficients), with tangent ogive projectiles having form factors as high as 1.32 i7. For comparison, the M855 projectile offers a 1.166 i7 form factor, despite not being particularly well streamlined. Finer projectiles compatible with the 5.56mm round offer i7 form factors as low as 1.09. Even when magazines allowing longer ogives are used – which it should be noted also would allow the use of longer and finer 5.56mm projectiles – the available relative space is still not significantly greater than that of the 5.56mm and 7.62x39mm cartridges. Further, as of yet there do not seem to be any manufacturers making .277″ projectiles with ogives designed for these longer magazines, and thus they only offer a velocity advantage to handloaders seating existing short-ogive bullets less deeply in the case.

This means that – at best – the 6.8mm SPC round can accommodate projectiles with a similar ballistic shape to the M855 round. Improved projectile shapes – including some that would be compatible with the 5.56mm standard – are not compatible with the 6.8mm SPC cartridge when loaded to standard magazine lengths.

This is further exacerbated by the 6.8mm’s restrictions on fineness ratios. The fineness ratio of a projectile is the ratio of its length to its diameter, and this is a factor in the projectile’s ballistic coefficient (typically, bullets with high fineness ratios have better ballistic coefficients). Because of the 6.8mm SPC’s wider projectile, accommodating higher fineness ratio bullets (such as M855A1-style lead-free projectiles) is more difficult, and more significantly reduces the case capacity of the round. This is closely related to the relative capacity of the round.

Compared to rounds like the 5.56mm or 7.62x51mm, the 6.8mm SPC has a poor relative capacity. This is the ratio of the case capacity to the cross-sectional area of the bore, and is an important predictor of performance. A ballistically ideal round propels a bullet with a high sectional density and high fineness ratio at high velocity. The relative capacity of the round is closely related to that round’s ability to propel high sectional density bullets at high velocities. A good example of this is given by comparing the 6.8mm SPC to the 5.56mm Mk. 262, with bullets of identical sectional density, using the simple Powley computer available at


A 5.56mm round compared to a 6.8mm round. Note that the 5.56mm has a higher relative capacity by 25%, and that it also has a a considerably higher muzzle velocity. This is because a round’s relative capacity is closely related to its suitability for propelling bullets of a given sectional density to higher velocities. The parameters for these calculations were chosen to keep the comparison constant. Both rounds are operating at the same pressure (the MAP for 6.8 SPC; 55,000 PSI), and both projectiles are based on real projectiles (the 77gr 5.56mm being based on the Sierra 77gr projectile from Mk. 262, and the 118gr projectile of the 6.8mm SPC being based on the Sierra 115gr projectile, with mass increased to keep sectional density constant with the 77gr 5.56mm projectile).


However, the relative capacity does not tell the whole story. A round with a lower relative capacity may have a higher velocity with projectiles of a given sectional density than another round, if it develops more pressure. Higher pressure cartridges are both more thermodynamically efficient as well as more mass efficient than lower pressure ones; they require less case volume (and thus less case mass) to produce the same velocity. In this, too, the 6.8mm falls behind, for reasons that will be explained below. Current 5.56mm ammunition (with the notable exceptions of M855A1 and Mk. 262) has a maximum average pressure of about 58,000 PSI, meaning the results shown above are somewhat muted versus reality. Further, while older Mk. 262 ammunition produced pressure comparable to the M855 round, current Mk. 262 ammunition utilizes more thermally stable propellants than previous 5.56mm rounds, allowing a MAP of about 68,000 PSI. Because the Powley computer was not designed to provide accurate calculations at pressure levels this high, I will not use the computer to produce data for this pressure level. From an 18″ SPR barrel, however, the Mk. 262 round typically produces velocities of about 2,800 ft/s, which translates to 9.3% more energy than the example above.

It’s therefore useful to be able to quantify this additional factor of pressure in some way. While it is not generally used in the relevant literature, I have chosen the term “internal specific energy”. To calculate this, take the relative capacity value and multiply it by the maximum pressure (giving units of lbf/in in English, or N/cm in Metric). This value is a hint only, as total work performed on the bullet is only roughly represented by the maximum pressure; for example, a round with slower-burning propellant may give higher velocities with a given bullet than one with faster-burning propellant, despite both having the same maximum pressure. It’s therefore wise to use this quantity only as a guide for sound cartridge design.

How, though, should we compare the pressures of 5.56mm and 6.8mm? 5.56mm has a given maximum pressure of about 58,000 PSI, but what about the higher pressure Mk. 262? Should only cartridges of the same pressure be compared? The answers to these questions depend on the purpose of the analysis, however for military rifle cartridges pressure is most important for its relationship to the strength and fatigue life of the locking mechanism of the rifle. All things being equal, a higher pressure round will stress a rifle’s locking mechanism more than a lower pressure one. However, the actual determiner for the stress exerted on the locking mechanism is a quantity of force not of pressure. The quantity that best represents the stress a given round will put on the locking surfaces of a rifle is bolt thrust (expressed in lbf in English and N in Metric), which is the force created against the locking lugs by the cartridge during firing. This quantity is the maximum pressure of the round multiplied by the maximum internal area of the case. For the purposes of this analysis, the maximum internal area of the case can be approximated by the formula below:


maximum internal area = pi * ([case head diameter – .033″] / 2)^2


To find the relative bolt thrusts of the 5.56mm and 6.8mm rounds, we find the result of the equation and then multiply it by the maximum pressure of each respective round.



Case head diameter: .378″

Maximum pressure: 58,000 PSI

Maximum internal area: 0.0935 in^2

Bolt thrust: 5,432 lbf


6.8mm SPC:

Case head diameter: .422″

Maximum pressure: 55,000 PSI

Maximum internal area: 0.1188 in^2

Bolt thrust: 6,537 lbf


The 6.8mm SPC round evidently puts much more stress on the rifle’s bolt than the 5.56mm round, which may cause the bolt to break sooner. For the 5.56mm round to produce as much bolt thrust, pressure would have to be increased to nearly 70,000 PSI. Therefore, the Mk. 262 Mod. 1 round, despite its very high maximum pressure of 68,000 PSI, actually puts less stress on a rifle bolt than the standard 55,000 PSI pressure 6.8mm SPC round. Since both rounds occupy comparable roles and both rounds were originally intended for the same platform (the Special Purpose Receiver, later Mk. 12 Special Purpose Rifle), it seems reasonable to therefore compare them directly against each other. First, we will calculate the rounds’ relative internal energies:

5.56mm (Mk. 262 pressures):

Relative capacity: 2.60 in

Peak pressure: 68,000 PSI

Internal specific energy: 176.8 x 10^3 lbf/in

6.8mm SPC:

Relative capacity: 2.06 in

Peak pressure: 55,000 PSI

Internal specific energy: 113.3 x 10^3 lbf/in


5.56mm’s 56% higher Eisp value suggests it has better ballistic potential than the 6.8mm’s. That, coupled with the 6.8mm’s shorter available ogive space indicates that the 5.56mm may be more ballistically optimal. To verify this, however, the two cartridges must be compared on more substantial terms.

As previously mentioned, it is beyond the limitations of the Powley Computer to generate velocities for the Mk. 262 round due to its high pressure. Powley calculations are also not truly representative of the performance possible from the 6.8mm SPC round, due to Powley being limited only to older IMR-type propellants, where the 6.8mm SPC performs best with newer propellants such as H335. For these reasons, when examining the ballistics of both the Mk. 262 round and 6.8mm SPC, I will be using non-calculated, non-empirical velocity figures based on the common performance of the two rounds. While the velocities used are not taken from any particular sources (as it is very difficult to find a truly controlled evaluation of the two rounds), I have done my best to choose figures representative of the actual performance of the two rounds from 18″ barrels with Spec II or DMR chambers.

To properly compare the two rounds, it will also be necessary to choose two different types of OTM projectiles in each caliber: Sierra’s tangent-ogive BTHP and Hornady’s secant-ogive BTHP. Ballistic coefficients for all four projectiles will be taken from the ballistic coefficient resource on my blog. In both cases, the Hornady secant-ogive projectiles give lower form factors and thus higher ballistic coefficients, due to their conforming more closely to the Sears-Haack body shape. Further, both lighter secant-ogive projectiles will be calculated with the same muzzle energy (and thus slightly higher velocity) than both tangent-ogive projectiles; this is representative of pulling a loaded tangent ogive bullet from the case and replacing it with a secant-ogive one.

To make an accurate ballistic comparison between the 5.56mm and 6.8mm rounds, we will use JBM Ballistic’s excellent external ballistics calculator. The settings used are reproduced below:

2015-04-04 02_07_43-JBM - Calculations - Trajectory

First, we compare the 77gr Sierra MatchKing BTHP with cannelure against the 115gr Sierra MatchKing BTHP with cannelure in terms of drop, wind drift, retained velocity and retained energy. The results are graphed in Excel and produced below:

2015-04-04 02_41_31-5.56 6.8 Sierra Compared Drop.ods - OpenOffice Calc

The Sierra BTHPs compared for drop. If the PEO Soldier criteria for maximum effective range is applied (the range at which the round has comparable drop to the M855 round at 500m when fired from an M4 Carbine), then the 6.8mm SPC has an MER of 450 meters, while the 5.56mm Mk. 262 has an MER of 510 meters.


2015-04-04 02_59_25-5.56 6.8 Sierra Compared Drift.ods - OpenOffice Calc

The Sierra BTHPs compared for wind drift. Counterintuitively, the lighter 5.56mm bullet bucks the wind better than the heavier 6.8mm.


2015-04-04 03_04_52-5.56 6.8 Sierra Compared Velocity.ods - OpenOffice Calc

The Sierra BTHPs compared for velocity. If a fragmentation threshold for the Sierra BTHP of 2,000 ft/s is used, the 6.8mm SPC will only fragment when it hits targets 210m away or closer. When the same fragmentation threshold is applied to the 5.56mm Mk. 262, it will fragment when striking targets 320m away or closer, a full 50% increase. Further, the 6.8mm enters the transonic flight regime (passing below Mach 1.3) at 430 meters range, and becomes subsonic at 590 meters. The 5.56mm enters the transonic regime at 580 meters range, and becomes subsonic at 770 meters.


2015-04-04 03_16_30-5.56 6.8 Sierra Compared Energy.ods - OpenOffice Calc

The Sierra BTHPs compared for energy. Beyond 300 meters, the 5.56mm Mk. 262 has 90% of the retained energy of the 6.8mm SPC or better. Between 470 and 700 meters, the 5.56mm actually possesses more retained energy than the larger 6.8mm.


Comparing the Sierra BTHPs illustrates the considerable shortcomings the 6.8mm has in both ogive length and velocity. Despite being larger and more powerful, the 6.8mm SPC 115gr quickly spends its advantage in muzzle energy and offers virtually no ballistic advantages beyond 300m over the 5.56mm 77gr Mk. 262.

The Hornady secant ogive BTHP rounds, however, are closer to each other in both ballistic coefficient and velocity, which should improve the 6.8mm’s lackluster ballistics somewhat. They are compared below:

2015-04-04 03_35_16-5.56 6.8 Hornady Compared Drop.ods - OpenOffice Calc

The Hornady BTHPs compared for drop. If the PEO Soldier criteria for maximum effective range is again applied, then the 6.8mm SPC has an MER of 470 meters, while the 5.56mm Mk. 262 has an MER of 520 meters.


2015-04-04 03_42_57-5.56 6.8 Hornady Compared Drift.ods - OpenOffice Calc

The Hornady BTHPs compared for wind drift. While the secant ogive helps close the gap between the two rounds, the 5.56mm 75gr BTHP still handles the wind better than the 6.8mm SPC.


2015-04-04 03_49_25-5.56 6.8 Hornady Compared Velocity.ods - OpenOffice Calc

The Hornady BTHPs compared for velocity. If the same fragmentation threshold as the Sierra BTHP is used for the Hornady BTHP, the 6.8mm SPC 110gr BTHP will fragment when it hits targets 250m away or closer. The 5.56mm 75gr BTHP stays above the same threshold when striking targets 340m away or closer, shrinking the gap between the two rounds to a 36% advantage for the 5.56mm. The 6.8mm Hornady enters the transonic flight regime (passing below Mach 1.3) at 500 meters range, and becomes subsonic at 680 meters, a considerable improvement over the Sierra load for the same caliber. The 5.56mm Hornady BTHP enters the transonic regime at 610 meters range, and becomes subsonic at 810 meters.


2015-04-04 04_00_54-5.56 6.8 Hornady Compared Energy.ods - OpenOffice Calc

The Hornady BTHPs compared for energy. The higher ballistic coefficient of the secant-ogive Hornady BTHP has improved things for the 6.8mm SPC. Only beyond 490 meters does the 5.56mm 75gr BTHP have 90% of the retained energy of the 6.8mm or better, this time. With the ballistically superior Hornady projectiles – though they come very close – the 5.56mm never exceeds the retained energy of the 6.8mm.


What this analysis makes clear is that the theoretical limitations of the 6.8mm SPC have a very real impact on its ballistic performance. Despite being designed to improve the performance of SPR-type rifles to medium ranges, the 6.8mm SPC when loaded with Sierra projectiles offers no improvement over current 5.56mm Mk. 262 ammunition except in terms of raw energy provided at ranges below 300m. Even with the ballistically superior Hornady BTHP projectiles, the 6.8mm SPC sacrifices important characteristics such as drop, wind drift characteristics, and a longer maximum fragmentation range for an advantage in muzzle energy that becomes increasingly small as distances approach 500m.

It must be remembered, however, that modern Mk. 262 did not exist at the time of the 6.8mm SPC’s development; the Mk. 262 ammunition at that time produced up to 200 ft/s lower muzzle velocities than current ammunition. Compared to that early ammunition, the 6.8mm SPC would offer a more substantial advantage in energy at short-medium range, even with a less impressive ballistic coefficient. However, at the same time the 6.8mm SPC’s chamber dimension issue had not yet been solved, and by the time it was solved (twice – by the Spec II chamber and by the DMR chamber), modern, high-pressure Mk. 262 ammunition had become available.

None of the above is intended to say that the 6.8mm SPC cartridge is unwanted or isn’t useful. The round offers hunters a 50-state legal medium game round with a good selection of effective bullets and accurate factory loads, that is compatible with the AR-15 rifle after relatively minor modifications that can be made with few tools and relatively little effort. Its additional available energy certainly makes it a more comfortable round to use for this task than the 5.56mm, while it has considerably better ballistics – especially with secant-ogive projectiles such as the 110gr Hornady V-Max – and projectile selection than the 7.62x39mm round.

In fact, had the 6.8mm SPC been introduced in the 1930s or ’40s, or had it been introduced as a dedicated medium game round (a sort of latter-day .30-30 to the .223 Remington’s .25-35, perhaps), I would have never taken the time to write the above analysis. It is the round’s serious limitations in the role for which it was designed – as a designated marksman rifle cartridge – that has made me take a closer look at its capabilities versus the round it was intended to replace. And after that, I am still a bit puzzled by it.

Nathaniel F

Nathaniel is a history enthusiast and firearms hobbyist whose primary interest lies in military small arms technological developments beginning with the smokeless powder era. In addition to contributing to The Firearm Blog, he runs 196,800 Revolutions Per Minute, a blog devoted to modern small arms design and theory. He is also the author of the original web serial Heartblood, which is being updated and edited regularly. He can be reached via email at


  • MrDakka

    100 Internet points for explaining how the Sears Haack body is relevant to bullet design.

    • mig1nc

      I wonder if anybody has ever used a sabot to propel a perfect Sears-Haack shaped projectile?

      Thinking back to the Steyr ACR prototype which fired saboted flechettes from a bullpup.

      • Early SPIW concepts were just that.

      • Kivaari

        Flechettes were exceptionally poor performers. Picattiny labs tried them in the late ’80s, and found they poke little needle sized holes with poor lethality. Circa 1989 Army times had some stories on the dart projectiles.

        • There are some gel tests available for the high velocity single flechettes that show them yawing. Do you have any more info on the Picatinny tests?

          • Kivaari

            Sorry, I left it behind when I retired. I still have a letter from Fackler along with a, new then, 6.5mm Carcano bullet test he had done. He said it wasn’t to do anything in the JFK tests, yet it showed up in Wound Ballistics Review. From memory it was V1N1 of 1995. It will blow the socks off the JFK conspiracy folks. As it shows how, really how, Oswald did it. It was done by a pair of Doctors Lattimer and others. It is better than the Warren report. Real science.
            I first encountered the best material after reading Exell’s AK47 Story. I used the footnotes to source articles. The University of Washington provided me several inches of research studies out of China, Yugoslavia and Sweden in addition to some US army material. It is how I met Dr, Fackler and joined the International Wound Ballistics Association. After he flattered me on my knowledge of knowing what questions to ask. I will look around I may still have a couple inches of the studies that I did not leave at the PD when I retired.

        • mig1nc

          Indeed, but I was rather referring to the use of a sabot to propel and stabilize the projectile in the bore. You could theoretically make a Seas-Haack with an air pocket like the 5.45×39 to facilitate yawing and fragmenting. Or they could look at bonding various metals to get something that would penetrate and still perform in soft tissue. Just theorizing. It’s fun to think about what could be. Especially since so many advances in bullet construction have occurred in the last 30-40 years.

          • Kivaari

            The US Army tested them in rifles. Failures. They are less likely to tumble, yaw. than 5.56mm. The reason being the fins keep it point on. The artillery fired projectiles often made massive wounds because the dart hit an intervening object, barbed wire between the gun and the target. It was common to see such wounds in VC/PAVN soldiers being treated by US Army surgeons. The thinking was, “Wow, these leave nasty wounds, what if we put them in a rifle.”. So they did and found that without being damaged while in flight, they poked little needle holes.
            I wish I still had the reference material. I left behind at the PD when I finally retired the second time 13 years ago. The Adam Henry deputy Chief wouldn’t send them to me when I requested.
            You may find a source among Facklers material, as he is the one that told me about it in a personal letter. He was arguing with his fellow officers stationed at Picatinny. He was at the Presidio at the time.

          • And, it’s worth noting, the 7N6 bullet design apparently does nothing to help alleviate the fleet yaw problem.

          • mig1nc

            Thanks for the reply! Neat info.

    • Now I have 101 Internet points!

  • Ryan

    This all confirms my wildcat idea that I’m going to try to sell to Remington. It’s a 6.8 SPC necked down to .22, I call it the 5.56x43mm. Think it’ll catch on?

    • jcl

      Make it tumbles like 5.45×39 and add hardened steel core.

      • Kivaari

        The 5.45mm Soviet round performs poorly in tissue. The testing done by the US Army, with guns from Robert Brown SOF, showed that in living tissue and gelatin tests the 5.45mm performed poorly compared to M193 and M855. The air pace in the nose of the 5.45mm allowed the core (lead and mild steel) to upset and yaw. The heavy jacket material did not fragment like the 5.56mm. Thus through intestines and muscle tissue the bullet left a permanent wound channel the shape of the bullet, however it was oriented at the time of passage. A lung hit, without bone interaction on entry, left a modest wound. A sucking chest wound. A hit in the liver or fluid filled stomach showed more destruction as expected. A bone strike will be dramatic, just as with any modern rifle round since 1890. Comparing the 5.45mm to the 7.62mm Soviet or 5.56mm NATO showed the 5.45mm was the poorest performing round in tissue. If the 5.45mm had a thinner jacket, performance would most likely improve.

        • Yeah, I think 7N6 is a bit overrated. It works for what it was designed for, but there’s a lot better out there these days.

          • Dolphy

            Y’know,given advancements made since 1958, I’m pretty sure that 5.56×45, while a fair light game and ornery cuss round, there must be something better these days, if only all your work didn’t seem to be dedicated to validating your previously held opinions. Remember, nobody would be trying to find a replacement caliber to 5.56 if it were as perfect as you like to portray it as being.

          • Cite where I say 5.56mm is perfect.

    • Brandon

      Already a few out there. One is shortened a small amount so the 75 amax, 80 and 90gr VLDs can be used. The other uses the case at full length 43mm.

    • Actually, that was one of the calibers prototyped during the early days of the SPC program.

      It would roughly be a rimless .219 Donaldson Wasp, or a slightly shorter version of the .224 Winchester E4 and E5.

    • Kivaari

      Why bother?

  • Hokum

    I truly admire your thorough approach to writing the articles. A lot of new information to think of.
    When the second part of “The Rise And Fall Of The Light Rifle” coming out?

    • Big research articles like that have a way of not playing well with deadlines. I had wanted to release Light Rifle II this weekend, but it wasn’t ready in time and my 6.8mm SPC analysis was.

      When Light Rifle II comes out, though, I think I can say Light Rifle III will be right behind it.

  • hod0r

    imo the only shortcoming of 5.56 is lackluster external ballistics at rather long ranges and a good solution to that problem would look more like a 6mm SAW (or 6mm HAGAR) than a 6.8 SPC. terminal performance is better controlled with bullet design (rear-heavy, spoon tip, controlled fragmentation) than making the bullet fat at the expense of external ballistics. hitting a target in the first place should be the first priority, a fatter bullet won’t help if you miss.

  • Chester Copperpot

    I stopped reading when you claimed it was meant to be a precision cartridge. Get your facts straight.

    • Are you saying Chris Bartocci’s history of the round is wrong? Do you have another source?

      • Brandon

        Try Cris Murray

        • He was in the Army Marksmanship Unit. But not a precision cartridge, got it.

          • Kev

            “He was in the Army Marksmanship Unit. But not a precision cartridge, got it.”
            Then his 7x46mm round is also a “sniper” round…, [sarcasm] Why would he ruin an MG42 to test this round in a machine gun, if he wanted a ‘sniper” round is beyond me….[/sarcasm]
            I don’t know the guy. I just read a few things he posted here and there, and even I can tell, you know nothing about him, or the 6.8.

          • I never said the 6.8mm SPC was a sniper round. I said it was developed as a precision round for the Mk. 12 SPR, which is a matter of historical record.

  • whskee

    Great analysis! When I was last deployed, the Mk 262 was in ALL of our mags, and that was the going recommendation among a lot of different teams. Not saying it’s the magic bullet, but I never heard anyone gripe about it either. I got invited out to a wild hog hunt and they were using the commercial equivalent. Had some doubts going in, but it worked exceptionally better than I thought it would, and kills were clean and quick. It’s good-to-go in my opinion.

  • ghost

    Yeah, whatever he said…….

  • Zebra Dun

    I’ve often read where the 6 mm bullets are sometimes known as the most humane of projectiles. The 6.5 mm Arisaki rifle I once had was more accurate than I could shoot it, tack driving accuracy, yet when military style bullets were fired into various media it never did the damage of other rounds. The same with my brother’s old 6 mm Carcano the bullets of military style simple zipped right through anything the bullet hit, if you could hit it as that was more shotgun than rifle.
    Could it be the shape and size/weight is too stable?

    • Marc

      the round nose bullets of the late 19th century were all very stable and zipped right through soft tissue, but nonetheless causes severe damage when hitting bone.

    • I think that perception comes from the sorts of military FMJs that were common surplus ammunition for a long time, especially the 6.5mm Carcano with its FMJRN bullet.

      Keeping bullet design constant, I can’t think of any special characteristic the 6.5mm rounds possess in this regard.

  • JoelC

    Good analysis. One of the things that isn’t factored into this is barrel length though. 6.8 spc was supposed to be optimized for shorter barrel lengths.

    I know people that hunt with it and it leaves big holes with the right bullets, but people have to be pretty familiar with their drop rate to take coyotes at distance.

    I’m not at all a fanboy for 6.8spc. Yes it performs well in shorter barrels, delivers more energy at closer ranges, and can be loaded with heavy bullets at subsonic velocities… But so can .300blk and it performs those jobs without a different bolt, decreased mag capacity, and more internal stress.

    A new round in a new gun is more likely to be the replacement for 5.56mm nato than any of these drop in replacements.

    One last thing: 5.8x39prc? Is that a round I’m unfamiliar with or do they mean 5.8×42?

    • I didn’t want to get into barrel lengths because that is a whole other can of worms, and would have quintupled the length of the article. Suffice it to say that from shorter barrels and with lighter bullets, the 6.8mm SPC offers a lot of power up front, but disappointing long range performance.

      It doesn’t appear that the 6.8mm SPC retains muzzle energy any better than 5.56mm when you cut down the barrel, though. If it does, maybe a little. Unfortunately, velocity figures are very misleading in this regard.

      The “5.8×39 PRC” is supposed to be the 5.8×42 Chinese, yes. It’s an error by the author of that book.

  • herb

    This is a whole lot of technical BS.

    • Steve Zahn

      I know this picture doesn’t really apply,but I just saw it for the first time and LOL’d. So I was looking for an excuse to use it. Ha, sorry

    • Khand-E

      Yeah I know, I mean who actually uses empirical data and actual research to come to a conclusion, clearly BIG BULLIT = BETTER BULLIT is much more sound reasoning.

    • hkguns

      Thanks for you valuable input herb.

      Dang, all the intermediate round fan boys are all running around butt hurt.

      Good article. I will need to read it over a few times before I fully comprehend what you are saying.

  • Dillon

    Isn’t this where you say on the internet “LOL”? Did he take half the charge powder out to get that performance? Crack me up….

  • TechnoTriticale

    It might have been worth emphasizing that the discussion is about SAAMI 6.8SPC, and not SPC-II loaded hotter, 6.8 ARP, “6.8×43” or other variants that might or might not offer improved ballistics.

    I suspect that any “better than 5.56mm” development that contrains itself with “must work with existing AR-15/M16 lowers” is going to be a bundle of compromises. 300BLK comes to mind.

    • Kev

      Actually Chris Murray’s specs for 6.8 were closer to the SPC-II specs. Remington screwed the first one. Nobody uses those specs anymore.

    • I think you’re right. I’ll think about doing an edit where I clarify that whole mess.

      • nova3930

        I think it would be worthwhile. I’ve said before that I would not choose 6.8 as a combat cartridge for a variety of reasons but with the appropriate chamber and barrel specifications it’s performance is somewhat better than what’s shown here.

        My preferred hog rifle is a 16″ SPC II with 1:12 5R barrel and I can load 85gr Barnes TSXs to nearly 3200 fps without pressure signs. That’s m193 level velocities with a 55 percent heavier bullet. Others braver than I have taken velocity higher than that.

        Even compared to mk262 it’s a slightly heavier bullet with an extra 700fps on it. It will through and through a 250lb hog nearly without fail no matter where you hit, regardless of bone, sinew or whatever.

        • For the record, my performance figures are based on Silver State Armory ammunition fired through an AR Performance barrel.

          Which is why I think it’s funny that we’ve got some imports from 68forums coming in here saying that – since I don’t think the 6.8 SPC is all that – I must be one of the Uninitiated.

          • nova3930

            Since you didn’t state that up front I think they’re legit comments because the capability of SAAMI spec ammo in a SAAMI chamber is terribly hindered.

            Secondarily are you talking about standard or “tactical” loads from ssa? It makes a difference as the standard loads are designed to be safe in any rifle Config including SAAMI spec.

            I’d suspect they’re standard loads since you list muzzle velocity as 2600fps for the 110gr bthp. Proper specs let you easily get North of 2800fps with 110gr nosler accubonds. So you’re basically shooting 110gr bullets at the same velocity as 75gr 556 loads. Nearly a 50 percent heavier bullet at equivalent velocity.

            I don’t know how that translates at longer ranges but under 200m it matters

          • I did state my references in the article. The performance levels aren’t taken directly from anything, they’re estimates based on standard pressure 6.8mm, by which I mean ammunition producing about 55,000 PSI from a Spec II or DMR chamber. The source for this – again – is here.

            At 2,800 ft/s, you are developing 16% more energy than a round with muzzle velocity of 2,600 ft/s with the same bullet, meaning pressures are going to be correspondingly higher. If you are loading 6.8 SPC – in any chamber – to 2,800 ft/s from an 18″ barrel, you need to back that load off, as it is unsafe.

          • nova3930

            Sorry I misunderstood where the data was coming from.

            Again though if the position you’re taking is SAAMI spec they’re still legit comments. The SAAMI spec has basically been demonstrated to be far to conservative. The very report you reference shows that with no adverse pressure signs even at 60ksi given proper chamber and barrel specs. As much respect as I have for Dr. Roberts the proof is in the pudding, whether mil originally specified it or not it’s within the realm of possibility.

            Given that the great minds at remington developed the SAAMI spec in conjunction with their inferior implementation of the cartridge is it any wonder they screwed up the pressure spec along with it?

            I’m not saying the 6.8 is some wonder cartridge it’s not. It has a specific niche that it’s good at (light rifle that hits above its weight under 200m) but that’s it. Really there’s a reason I only have one while I have a half dozen in 556. At the same time when the whole system is set up correctly the performance is greater than characterized.

          • The only time in the article I reference anything to do with SAAMI is when I am talking about the cartridge’s physical properties. My data references velocities for SSA ammunition fired through an ARP DMR-chamber barrel.

            At 60,000 PSI, the .422″ case head is producing a tremendous amount of bolt thrust, significantly reducing the life of the bolt and possibly endangering the shooter. Regardless of the great numbers you get from handloads at those pressures, they cannot be considered militarily relevant.

          • nova3930

            If the standard pressure loads you’re using aren’t SAAMI pressure what are they? Seems to be a semantic argument.

            Wanted to investigate the issue of whether the 60ksi load is actually unsafe or not. Unfortunately using the Lilja equations that are out there, I can’t even come up with numbers for an AR bolt that show the standard 5.56 55ksi loading to be safe, even disregarding their built in factor of safety of 2. I’ve got a mistake somewhere but can’t find it. Some of the literature I’ve found suggests using Von Mises stresses but I don’t think I have enough data for that, and in any event I’m not digging out all my old structural texts to go down that rabbit hole.

            However, just looking at the SAAMI proof load for 7.62×39, I’d strongly suspect the load is perfectly safe. The SAAMI proof load for 7.62×39 runs 67ksi to 71.5ksi, with a resultant bolt thrust of between, 10,182 lbf and 10,866 lbf, right at 25% higher than the 8,333 lbf I calculate for the 60ksi 6.8load.

            Granted 7.62×39 AR bolts are known for lower mean rounds between failure (MRBF) numbers, but that’s just fatigue, Drive up average stress and cycles to failure drops. I’d expect to see the same on the 60ksi 6.8 loads. Which to my thinking is an even better argument against the 6.8 as a military cartidge than some of what you’ve presented above. Cutting MRBF by half or two thirds is a significant operational issue. That’s increased spare parts costs, increased maintenance time and worst case, more hard failures in combat.

            Lastly, if I had to make a SWAG at it, I’d say the original 5.56 55ksi standard was chosen at least in part of maintain the MRBF of the bolt at a particular level to meet military specifications. I have no proof of that, but it seems logical given the available evidence that even a relieved AR bolt can sustain much higher forces, not to mention the fact that the Army chose to drive the M855A1 pressure up to 63ksi…

          • SAAMI pressure =/= SAAMI spec. I did not use SAAMI spec chambers (for the thousandth time, I used an AR Performance barrel with a DMR chamber as reference). The ammunition I used as reference ran right up against the 55,000 PSI limit. Keep in mind, this is representative of a mass-manufactured cartridge with about a 60,000 PSI MAP*. So the comparison was in fact heavily weighed in the 6.8’s favor.

            *Maximum Average Pressure is essentially the “rejection limit” for a lot of ammunition. If a tested batch of ammunition produces an average pressure level above this limit, it is rejected. Therefore, if the 6.8 SPC has a SAAMI MAP of 55,000 PSI, the ammunition I used (SSA) was running so hot it was bordering on being rejected by SAAMI standards.

            Finally, compare the velocity figures I am using (110gr at 2,660 ft/s) with those given by Mad_Gorilla in a comment below:

            “A current 6.8 SPC II with an 11.25 twist and 5R rifling is what it started out as. It can give a 110 gr. HPBT 2600 fps out of a 16″ barrel, 2650 out of 18″.”

            Is 60KPSI 6.8 SPC safe? Yes, probably, if you are just shooting at the range. However, it’s unrealistic for military ammunition (which is the subject of this article). The reason being that pressure is not a fixed quantity. Pressure will vary if ammunition is cold or hot or fired in a cold or hot chamber. In fact, M855 ammunition with a MAP of 58,000 PSI is capable of producing 90,000 PSI in a chamber that is too hot (300 degrees F). Because of the 6.8 SPC’s 27% higher bolt thrust at a given pressure, a 60KPSI load fired in these same conditions could put stress on the bolt equivalent to a 5.56mm round producing 120,000 PSI. I would NOT consider that safe.

            The original .223 pressure standard was 52,000 PSI. Never has 5.56mm had a pressure standard of 55,000 PSI. When M193 was first being standardized in the military, it failed to meet performance specifications, and it was raised to 58,000 PSI.

          • LilWolfy

            60,000psi in the AR15 with a .421″ case diameter is not safe, at least not if you plan on shooting the gun in any sort of normal volume. You can produce hand-fit extensions and barrels with special bolts, using a certain grade of steel that will hold up a little better, but you have narrowed the Factors of Safety so much at that point that there is literally no room for error from a manufacturing perspective, and the barrel, extension, and bolt manufacturing has to be perfect all the time.

            So does the brass and ammunition manufacturing. You basically have a wildcat at that point. Not even the 5.56 does well with the existing pressures and a much narrower cartridge diameter at .378″, with substantially more chamber wall thickness and less bolt thrust.

          • nova3930

            Again, read the referenced report prior to commenting. Unless you can tell me what the combined ultimate shear load on an AR bolt is, or the maximum hoop stresses the chamber is seeing compared to the maximum for properly dimensioned 4150CMV, you’re speaking of things you really don’t know the answer to.
            The calculations I’ve attempted have indicated that 58ksi M193 isn’t even safe wrt shear loads on the bolt lugs. My calculations came in at approx. 4000lbf compared to nearly 6700 lbf for a 58ksi M193. Been busy but I need to re-visit my calculations for about the 5th time to make sure I don’t have a bonehead error, and then if there is no error possibly break out my structural analysis texts to determine some better methodology, although if it involves von-mises stresses the chances of my going further is basically nil.

          • nova3930

            Oh hey would you look at that. Utilizing rim diameter as the ID, which is conservative, 5.56 @ 63 KSI chamber pressure results in a hoop stress on the standard AR barrel extension of 67.5 KSI. 6.8MM @ 60KSI results in a hoop stress of 65.7 KSI. That’s so unsafe .mil decided to use it every day of the week.

          • LilWolfy

            Your calcs are off I think. I used 6.8 SPC II reamer print for PTG which shows .422″ +/- .001 fractional. Even if we take the more generous 5.56 NATO reamers from Clymer, PTG, and JGS-all of which have a base diameter over .3800″ for the 5.56 NATO, and run the 63ksi chamber pressure you indicate compared to the 6.8 SPC II at 60ksi, the 6.8 still has more hoop stress, and those 5.56 pressures don’t give me a good feeling either.

            I’m using the Lassen gunsmithing online calculator for thick wall hoop, and a production nominal minimum of .735″ for the relief cut at the barrel tenon under the extension, which is the weak point in the system aside from bolts.

          • nova3930

            I used the thick wall hoop stress equations out of my structural analysis texts from way back in college. It’s possible there’s an error as I did it quick and dirty with an incomplete barrel extension drawing. I took the nominal od and subtracted the rim diameter of both cartridges to get the wall thickness thinking that would be somewhat conservative for that area of the extension. At that area the factor of safety was still over 3 assuming 4150 cmv

          • LilWolfy

            The other thing is that if you address bolt thrust with increased strength with the bolt geometry and metallurgy, where does the failure point gravitate to? Chambers start to egg out quickly, which is bad ju-ju for a military carbine. Case head separations and gas leakage into the breech at high pressure with a fully locked bolt isn’t such a great idea, whereas a shorn lug or two is a fail-safe that lets you know you’re in a bad place, without re-designing the gun into AR10 dimensions for the chamber walls, upper receiver, barrel nut threads, BCG, etc.

            That is the biggest hurdle that a lot of people can’t get past when trying to force larger diameter cartridges into the limitations of the AR15’s dimensions, and increase the pressures. The gun simply was not built around any of these cartridges, so the pressures have to be adjusted accordingly.

            Now imagine a mass-produced military barrel and extension, where the threads aren’t mated like a Swiss watch, and where is the failure point? When a certain unit ran a pyramid test with at least a dozen 6.8’s back in the mid-2000’s, their conclusion was the gun was unsafe, so they rejected it. They put over 100,000 rounds through the guns collectively, or at least attempted to, and walked away from it. 6.8 proponents had to be removed from Fort Bragg after refusing to accept “no” as an answer. The Murray chambers have been around since day 1 before the Remington-PTG fiasco.

            The FBI terminal ballistics lab laughed at the way the 6.8 terminal testing had been done, and the FBI was not impressed with the amateur antics. They submitted a varmint bullet compared to the other calibers all using a Sierra Match King OTM for 6mm, 6.5mm, and 7mm. That’s how they came to the conclusion that the 6.8 diameter was superior….no really. I could list more stories but they are best left for a discussion offline. The whole program was a big screw-up from the get go. People lost their jobs over it, they were so unprofessional in the way they conducted their campaign to try to promote the cartridge.

            The cartridge itself isn’t bad. The best thing they could have done was pursue the quarterbore. That way, the industry response could have been spent on developing the .257 projectile line to bring more boat tails to the table and get the 100-120gr pills BC’s up. Quarterbore lovers would have benefited from that, whereas the 6.8 has done nothing for the .270 Winchester really.

          • Is that pyramid test documented anywhere?

            6.8 terminal testing appears to be a mess, from my perspective. Some data was not recorded that are highly relevant, and there are serious doubts about the tests’ objectivity.

            Do you mean to tell me that the picture below:


            Actually compares all test cartridges, and that the trials included V-Max projectiles in the 6.8mm caliber and SMKs in all other calibers? What the hell? I had assumed the four flanking cartridges were all test rounds and the middle was a later production round.

            Also, I would love to hear more, if you are willing to email me at this address:

          • LilWolfy

            Yes, and when the obvious was stated, they pulled the tip off the V-MAX and voila-magic! No more V-MAX, just an OTM like the rest! They were sent packing after that too. It’s pretty hilarious really. Bridges were burned in almost every professional exchange.

            The pyramid testing was documented, but due to the nature of the unit that conducted it, I doubt we’ll ever see it. I’ve independently confirmed it with 2 different reliable sources. It’s one of the main obstacles the 6.8 hit in the SOF community behind the scenes, and a lot of feelings were hurt, even though the guys doing the testing were just doing what should have been done by manufacturers. The response from the 6.8 advocates after that was that “Army brass is trying to kill it.” Most big Army brass didn’t even know or care what was going on with the program. If you put the two cartridges on the table in front of the procurement weenies, they couldn’t tell one from the other.

            The civilian market success of the 6.8 SPC has been largely because there has been a hunger for more horsepower from the AR15 since the AR15 was introduced, and a lot of people who subscribed to the “real man’s” caliber arguments in the wake of the introduction of the 5.56 latched onto 6.8 when the advertising campaign launched.

            The benefits of that have been a lot of people gravitating to AR15’s for hunting, even if a 5.56 Barnes 70gr TSX load would exhibit practically the same type of terminal performance as a lot of the lighter weight 6.8 hunting loads. Perception is reality for a lot of hunters, and trying to fight that means negating what grandpa and dad have passed down, which is a fool’s errand in most cases.

            People will not hear what you say, they will only notice how they are feeling when new information is introduced that challenges the wisdom handed to them from uncle Festus, or their new source of wisdom in the digital age. To suggest data contrary to what has brought them a lot of satisfaction appears like heresy or some type of agenda. I have never seen a more vitriolic environment between gun owners when the 6.8 is brought up and compared to something else.

          • Kivaari

            I found that it needs a 20″ barrel to get the 2350 fps in a 7.62x39mm.
            We chronographed both in a Yugo M59/61A and a Yugo M70. The Chinese ammo we used was the most consistent military ammo I had ever fired.

          • iksnilol

            Most tests and data I have seen show 715 m/s as the standard velocity out of 40 cm barrels. Maybe temperature and pressure affected your findings?

          • Kivaari

            It was moderate weather. It happened anytime we ran chronograph tests. Regardless of being a Chinese rifle or carbine, Hungarian, Finn or Egyptian. The “books all showed the 2350 fps as being “the load”, yet it only happened to meet that in the SKS. Every thing I could get ahold of in the 70s and 80s, Czech, Lapua and Chinese. In those days it was uncommon to find 7.62x39mm ammo. It was scarce enough that I reloaded Lapua using Berdan primers. 5.5mm Norma primers I got for free by the thousands because no one else had bought them. Ammo cost $360 per thousand in an era when 10 cents a round for 7.62mm NATO, .45 ACP and 8 cent .303 and 8mm were over priced. Until 67-68 I could buy US military ammo of most calibers for 3 to 5 cents, all courtesy of the National Guard Armory next to the high school.

          • iksnilol

            I just find it strange is all. Since all other chronograph data shows results different than yours.

            Also, regarding price, I don’t doubt 7.62×39 wasn’t expensive but you got to adjust for inflation. A dollar from the 60’s and a dollar from 2015 aren’t worth the same.

          • Kivaari

            That’s the point. I can buy 7.62mm for 36 cents a round today. I was paying that in the late 70-early 80s. So adjusted for inflation, would that make it $5 a shot today? When I was making $10 hour it was a big bunch of money.

        • LilWolfy

          An 85gr TSX at 3200fps from a 16″ barrel IS a major pressure sign if the case capacity is 34.8gr of H2O.

          What load data are you using to get those speeds? You’re well above 60,000psi unless you have a custom blended powder, and even then, you’re in the high 57ksi and above range at least.

          The fastest speeds in Accurate Powder’s load data are from a 20″ barrel pushing pressures way past the SAAMI MAP, and still not anywhere near 3200fps.

          You’re getting it with a 16″ barrel, literally 4″ less barrel. If this does not raise a red flag with you, I don’t know what more to say.

          • nova3930

            I’d suggest you read the referenced report before you comment….empirical data trumps theory after all….or at least it does in my world of engineering….

      • Andrew

        I am also interested in reading more about the different specs for 6.8. Maybe I’ll peruse the forums.

    • andrew

      300blk does have its place in suppressed SBR’s, but yeah, I agree. 556 is hard to beat in its form factor.

    • LilWolfy

      The benefit that staying within AR15 magwell brings with it is that it sets a certain load profile for the soldier’s load, when talking about military cartridges, and sets a certain recoil limit, when talking about a hunting platform.

      Both of those limitations are major positives in the long run.

  • ed308

    Why use IMR 3031 powder? I’ve reloaded 6.8 for years and 3031 not a popular choice for people who reload 6.8. Too slow, better suited for cases with a larger case capacity like 30.06 or .308. AA220, 10X, and H335 are a better choice for 6.8.

  • Kev

    Only some spin doctor would twist things around this bad to make his opinion look valid.
    First of all, the idea and requirements for the 6.8 spc are exactly the opposite of the SPR concept and the 18 inch barrel you try to misleadingly connect it to.
    The 6.8 was made to maximize TERMINAL BALISTICS out of SHORTER BARREL carbines, BASED ON AR-15, out to mid ranges.
    And in that respect the 6.8 sits head and shoulders above everything else. The 6.8 dominated the FBI terminal effectiveness tests ever since it was released.
    Do you really think Chris Murray and the guys at AMU don’t know how to make a SPR cartridge, if they wanted to make one? Do you really think you are so awesome to know better than those guys what it takes to make a SPR cartridge?
    For the tenth time you are wrong and no matter how you would twist and try to mislead the readers, you still come out short.

    • Dan

      and thus you make the argument for 300blk.

    • The 6.8mm SPC was developed for the Mk. 12 SPR (with an 18″ barrel). That is why they both have “Special Purpose” in the name.

    • Sergey

      “Only some spin doctor would twist things around this bad to make his opinion look valid.First of all, the idea and requirements for the 6.8 spc are exactly the opposite of the SPR concept and the 18 inch barrel you try to misleadingly connect it to.
      The 6.8 was made to maximize TERMINAL BALISTICS out of SHORTER BARREL carbines, BASED ON AR-15, out to mid ranges.
      And in that respect the 6.8 sits head and shoulders above everything else. The 6.8 dominated the FBI terminal effectiveness tests ever since it was released.
      Do you really think Chris Murray and the guys at AMU don’t know how to make a SPR cartridge, if they wanted to make one? Do you really think you are so awesome to know better than those guys what it takes to make a SPR cartridge?
      For the tenth time you are wrong and no matter how you would twist and try to mislead the readers, you still come out short.”

      Wonderful, Kev! Hey, look up Fegelein’s analysis that’s about 24 hours old now. He really tore this clown several new ones.

  • Brandon

    “apprentice small arms know it all” should tell the tale. He thinks he’s a know it all…maybe not know so much. Reads a lot but can’t figure out the link between reading and practical application. Seems like someone writing an article to all about something would have checked with several real professionals on the subject matter.

    • Not sure what this has to do with ballistics…

      • Brandon

        After Remington dropped the cartridge and SSA took over production of the test ammo when Barrett was involved no company has tried to push this through the US military. SSA and LWRC tried to sell the idea to foreign NATO countries(sold it to Jordan and Saudi for special use troops). The American hunters have adopted the 6.8 and that is who keeps it alive today. I believe you are apx 8 years late comparing a cartridge that is out of the running for mil use.
        Talk to Steve Holland about why he wanted the 6.8 for the 5th Group.
        If Remington had not made the chamber freebore mistake and a number had not been transposed on the reamer drawing and the “Extreme” bullet had not caused problems during the trials when testing Barretts firearms the outcome may have been much different.
        Many people wasted a lot of time trying to prove there was more performance available if manufactured correctly and the 6.8 would have saved lives which was Hollands main reason for wanting the round

        • Khand-E

          Do tell how the 6.8x43mm would’ve magically saved lives, I’m dying to hear it.

          • Brandon

            Have you ever had to put 4-5 rounds in a guy before he drops?

          • Khand-E

            No, probably because I can actually aim a gun properly, and I imagine US soldiers are on average better shots then me.

            And even if they somehow did miss horribly, firing 4-5 shots into someone with a high rate of fire, low recoil gun wouldn’t exactly be a huge problem, the target is still quite incapacitated or dead with much haste.

          • Brandon

            While you’re busy aiming, putting multiple shots in Achmed and reloading Achmed’s team is filling your ass full of holes. This is not a one on one or a video game. Ask any door kicker if firing multiple shots is a waste of valuable time when there is another gun in the same room firing at them. Get hit in the plate once, I bet you think about ways to prevent that again.

          • n0truscotsman

            So is 6.8 SPC supposed to “knock ’em cold with one”? The same arguments are used in favor of the more powerful 7.62 NATO, yet, the human body, being a resilient product of lengthy evolution, has proven itself resistant even against larger calibers.

            If the 7.62 is incapable of one shot stops all the time, then 6.8 will be even less so.

            “one shot stop” is an example of a unrealistic fantasy anyways.

          • Kev

            Khand, do you think real world is call of duty?

          • I’m not sure I understand this argument. M855 has been known to fail to yaw and fragment, even at close ranges before, right? Fleet yaw problem and all this.

            How does the 6.8mm SPC round (or any other round, for that matter) solve this with standard FMJ bullets? In theory and in practice, the larger caliber 6.8mm projectiles yaw later than 5.56mm projectiles, and so far as I know they are just as subject to the fleet yaw problem.

            Most often when I bring this up, I am told that even if the 6.8mm SPC does not yaw, it will make a bigger hole and thus be much more effective than 5.56mm. This doesn’t make much sense to me, either. If 5.56mm fails to yaw or otherwise expend its energy in the target, it may give results close to a .22 LR. If 6.8mm SPC fails to do the same, wouldn’t it give results similar to a .25 ACP? Does anyone seriously believe that’s a serious jump in effectiveness?

            Of course, you can load the 6.8mm SPC up with better projectiles than the standard FMJ, but the same is true of 5.56mm, as well. Indeed, the military 6.8mm SPC had died a quiet death, while the 5.56mm has exploded into a bajillion different versions (Brown Tip, Mk. 262, Mk. 255, Mk. 318, M855A1, etc) that are exactly that.

          • Brandon

            Look for all of DocGKR’s posts from 2006-2009. There are photos of gel tests that show the performance of all 5.56 ammo and compares it to performance from different 6.8 ammo. There is no doubt the 6.8 has better terminal performance.
            We aren’t shooting paper so who cares if the 5.56 bullets have a better trajectory? That is why they make dials on scopes.

          • I am very familiar with Gary Robert’s work. There is a lot that is questionable to me about it, for starters how he managed to get an OTM of almost identical design to Mk. 262 to expand neatly like a JSP. Very curious, especially since Roberts insists those tests were not done with “that one batch” of V-Max-loaded “OTMs”.

        • I assume Holland wanted the round because he helped developed it.

          I agree that the 6.8mm SPC is pretty dead these days. I’m no stranger to historical articles, though, certainly.

          • Mad_Gorilla

            The 6.8 is far from dead. There are special ops guys using it, and both the Jordanian and Saudi military are using it. Like I said before, it is #2 in sales after 5.56 in the AR platform. Several of the better AR houses have added 6.8 models this year to their lineups.

          • Could you give me a source from the past three years of special operations using 6.8mm in combat?

            Really, I have a very hard time accepting what you’re saying (really? Nobody has a source for this #2 spot claim?) considering the runaway popularity of ARs in cartridges like .300 Blackout, 9mm, .22 LR, etc.

          • Don Ward

            It’s number 2 after .308, 300 Blackout, 9mm, .22, 50 BMG…

          • Mad_Gorilla

            I thought you said you’ve been lurking on 68forum? All this stuff has been posted over there. I’ve got a fair amount of experience with wildcats, and what goes into making them. For wet work, with heavy bullets, the .300 BO is pretty good, For anything else, its a pig. A new wildcat that handles both the supersonic side and the suppressed side is the .277 Wolverine. That’s the 5.56 case reworked for .277. Fits standard 5.56 mags, etc. It runs rings around 5.56, and most of the other AR cartridges. It absolutely thrashes the .300. Just because you haven’t kept up with things, doesn’t mean those things aren’t true. Crunching numbers on paper and drawing graphs far too often overlooks actual field performance. The 6.8 hits far above its weight, and those who have used it know that.

          • Does this mean you don’t have a source?

          • I’m afflicted with a neurological disease that prevents me from accessing internet forums directly, I’m going to need you to post links to the information on the 68 forums that supports your position.

          • Shutnik

            Aaaaaannnnd powned! Better get the liquid nitrogen; that burns looks HOT.

          • Brandon

            Well duh, I assume he wanted something more lethal then developed the round along with Murray and Lawton to suit the purpose. Read the articles man. They tested 6.5, 6.8 and 7mm bullets in case of the apx same size. The 7mm had the best terminal performance, that is why Murray is still working on a 7mm. The 6.5 had the best accuracy. They chose the 6.8 because it was almost as lethal as the 7mm but had a better weight range of bullets.
            Read Zak Smiths article from 2006, It was much more accurate than that thing you wrote.

          • Based on my ballistic charts, I don’t see how the 6.8mm is “more lethal” beyond 200m.

            What, exactly, do you take issue with about my article?

  • dhdoyle

    Hmmm… I believe you missed the point about the 6.8 SPC. It was designed to improve short range lethality on soft targets. It was also developed with the requirement that it use approved bullets (i.e., OTM). In that regard, it accomplishes its goal. It is much more effective than 5.56 anything. It is definitely not a long-range cartridge. Doc GKR has written extensively about the development and a bit about field trials of the 6.8 SPC.

    • Dan

      might as well use 300blk then.

      • Brandon

        I doubt that, the 300 is 200fps slower..Terrible round for anything more that 100yds.

      • Alex Nicolin

        .300 BLK with lighter (supersonic) bullets is even lousier. It’s basically 7.62×39 mm. It drops like a rock, has poor SD and energy retention, and less tendency to yaw and fragment.

        • .300 Blackout is ballistically pretty similar to 7.92×33, in fact.

          • Kivaari

            And, those have the ballistics of a 60mm mortar.

        • Kivaari

          Thanks, I have not figured out why the .300 Blackout exists except for use in suppressed rifles. It has nothing to offer users of non-suppressed rifles. As much as I like the 7.62x39mm it is a poor performer compared to the 5.56mm.

    • It was designed as a replacement for the Mk. 262 round in the MK. 12 SPR. The improved performance evolutions of which I have compared it against.

    • Mad_Gorilla

      The original design of the 6.8 was NOT what the Army ended up with after Remington screwed up the chamber drawings. A current 6.8 SPC II with an 11.25 twist and 5R rifling is what it started out as. It can give a 110 gr. HPBT 2600 fps out of a 16″ barrel, 2650 out of 18″. As far as range goes, it is fully capable of killing at 400 yds in the hands of a good rifleman with top 110 gr. loads.

      • The performance used in this evaluation was 110gr HPBT at 2,660 ft/s from an 18″ barrel, so very in line with the figures you cite.

    • Claire

      “Hmmm… I believe you missed the point about the 6.8 SPC. It was designed to improve short range lethality on soft targets. It was also developed with the requirement that it use approved bullets (i.e., OTM). In that regard, it accomplishes its goal. It is much more effective than 5.56 anything. It is definitely not a long-range cartridge. Doc GKR has written extensively about the development and a bit about field trials of the 6.8 SPC.”

      Hush, you may just hurt his fragile feelings. XD

      • You 6.8 fans really are making a fools out of yourselves.

  • McThag

    2002 called, they want their specifications back.

    Nathaniel, update your information or stop writing about 6.8. You’re embarrassing yourself.

    • toms

      This, or maybe he should compare the spec one loadings to the original m193. The same principles that made the mk262 can also be applied to the 6.8. My wilson combat tac load ttsx push 2700 fps from a 16″ barrel. Its not even in the same realm as any 5.56 load at any reasonable distance.

      • toms

        edit 110 grain ttsx the 95gr ttsx is 2950.

      • The M193 round was not military standard with any NATO nation at the time of the 6.8mm’s development.

        The 6.8mm was designed as a Mk. 262 replacement, so the comparison is fair.

      • Marc

        5.56 is limited to a stubby ogive because of the max OAL. 6.8 is limited to an even stubbier ogive for the same reason. there’s only so much you can do to improve the ballistic coefficient when so severely limited in ogive length. simply increasing sectional density by making the bullet longer (like Mk262) has rapidly diminishing returns in the form of reduced velocity.

        what’s really holding everyone back is the length of the AR-15 magazine well, designed to hold a 55 gr 5.56×45 in a thin-walled magazine and nothing more. LWRC’s Six8 COULD bring about a much bigger increase in external ballistics than Mk262, IF it gains enough popularity to be relevant and one of the many ballistically optimized loads of the countless wildcatters gains traction, but I have little hope for that.

        • There aren’t really any bullets optimized for the 2.32″ OAL, and further even assuming there were, the gains wouldn’t be dramatic.

        • Mad_Gorilla

          Cartridge OAL is limited by the magazine to 2.30″ in both calibers. Modify a mag and you can run 130 gr. long range bullets in the 6.8.

          • Or 80gr long range bullets in 5.56mm. 🙂

          • Marc

            even the 135 gr .277″ SMK has a very unimpressive ballistic coefficient compared to 6mm or 6.5mm long ogive bullets. there simply is no way to make 6.8 not suck at long range with its inherent limitations.

          • Mad_Gorilla

            The 135 was not designed for the 6.8, but for the .270 Win. It was intended for combat with 110/115 gr. bullets. Most experts will tell you a 5.56 has an effective combat range of 200 yds. The 6.8 can easily extend that to 300, and 400 in the hands of an expert shot. The average infantryman isn’t good enough to go much beyond 250 yds. especially with an M4 carbine that limits effective range even more.

            Even if the 6.5 can shoot farther, that extra range is wasted in the hands of the average soldier with an M4.

          • Is the PEO Soldier office not an expert?

            “Optimally, friendly forces will engage as the enemy enters the range overmatch area. This advantage is short lived however, since a quickly approaching enemy can move through this area in seconds. For example, according to The Encyclopedia of Land Warfare in the 20th Century, the effective range for AK-47 fired on semi automatic is 400 meters. The effective range for an M4 Carbine is 500 meters. The 100 meter difference provides a decisive range overmatch capability so long as Soldiers are proficient at hitting targets at the 400-500 meter range, which is why extensive marksmanship training is so critical.”

          • Mad_Gorilla

            What’re you smokin’ dude? An M4 with a 12-14″ barrel is NOT combat effective at 500 meters – 550 yds. That doesn’t mean you can’t hit with it that far out, but the ability to take a bad guy out at that range is minimal at best. Most of the guys I’ve talked to who actually used an M4 in combat have told me that 200 yds was a realistic combat range. Anything beyond that, they’re gonna call in the guys with the M14s, or the snipers.

          • I guess neither is 6.8mm effective at 500m, then…

          • scotchflavoredchewablevicoden

            Since when does the M4 have a 12″ barrel?

          • Kivaari

            Colt’s Commando with 10.3″ or 11.5″ as marked on the receivers. The M4 is the M4 with a 14.5″ on military issue .

          • scotchflavoredchewablevicoden

            I realize that… I was making the point that he’s incorrect with regards to M4 barrels.

          • n0truscotsman

            It really depends on what ammunition you are using.

            Mk 262 and 318 seem to be effective within the 500 meter range, sometimes a bit more, although, like with any other caliber, to include 6.8 and 7.62 NATO, that is entirely dependent on the rifleman.

            Most average riflemen aren’t capable of knocking down targets past 200 meters when you add the variables such as getting shot at right back and physical exertion are thrown into the mix. That assertion is generally true and was proven so back in World War I.

            In afghanistan, the most useful thing for outranging PKs and long range fire were 60mm mortars.

          • Dan

            Well most of the guys I talked to who use an M4 in combat say 6.8 fanboys are just mad their cartridge sucks. Seen the pictures to prove it

          • Mad_Gorilla

            It doesn’t suck, not even a little bit. You should come over and talk to a couple of the guys on 68forum who have seen it in action in the sandbox with the SOC guys. You just might change your mind.

          • Dan

            Well i was actually trolling, but..I think I will just stick with what I have, I don’t need a niche cartridge that doesn’t offer anything more than what I have now. I do admire your devotion to the cartridge though

          • Kivaari

            Not many AK rifles have good enough sights allowing skilled shooters to hit at 400m. Crude sights rule on AKs. Soviets shifting to the 5.45mm increased the soldiers actual hit count by 2.5 times over the 7.62mm. The 5.45mm is not as good as the 5.56mm in wounding power.

          • iksnilol

            Average Soviet AK has no problems hitting at 400 meters and suppressing at farther distance. The sights go to 800 meters for a good reason.

          • Kivaari

            I had around 25 AKs, and they were hard to hit with at those ranges. Crude sights. Valmets and Galils did better, good sights.
            Even using battle rifles in WW2 German and /Soviet soldiers using scoped rifles complained that it was near impossible to hit beyond 400 m. I have never met anyone that could reliably hit at 400 m using an AK. The biggest reason the Soviets changed to the 5.45mm round was to improve hits beyond 200m. The cartridge and muzzle brake on the 74, gave them a hit ratio 2.5 times that of the 7.62mm. Having sights calibrated to 800m doesn’t mean you can hit with them. It that were the case the rifles with 2000m settings must have really been good. Same for Mauser pistols with 500 m settings.

          • iksnilol

            400 meters for killing, further for suppressive area fire. Though if you know the distance then it isn’t much of a problem to hit past 400m. But of course, in combat you don’t know the range nor do you have time for accurate shooting so you are limited to a 400 meter range.

            If you have a scope, something like a PSO-1, then you shouldn’t have issue with 300-400 meters. But it isn’t unrealistic with irons either. Though I will admit, an AK isn’t my choice of longer range rifle.

          • Andrew

            In my limited experience, the effective range of an AK47 is around 300 meters. With our current crop of enemies, I don’t get too worried unless they are within 200. Not that I’m just gonna stand upright in the open even at 500. I do consider the 5.45 to be superior at almost any range. Not really sure why so many like the 7.62×39 so much.

          • Kivaari

            I, liked playing with the 7.62x39mm, having at one time around 25 AKs and as many SKSs. It is a fun round to plink with. In short range man on man combat it is OK. What I find amazing is so many people claim it is so superior to the 5.56mm. When real gun shot wounds are studied, while being treated, the 7.62mm doesn’t do as much as the 5.56mm

          • Marc

            no matter what it was designed for, there simply are no .277 bullets with impressive BCs. e.g. the .277 Berger hunting bulllet – they don’t even bother making a target bullet for .277 – has a worse BC than than any 6.5 mm of the same product line and three of four 7 mm bullets of the same product line have a higher BC. .277 bullets are high-BC no man’s land. even if there were any high-BC .277 bullets 6.8 couldn’t use them.
            and no, 5.56 isn’t limited to 200 yards.

          • Mad_Gorilla

            At normal hunting ranges, ie 300 yds and less, BC doesn’t even enter into the picture. 6.5 bullets that all the Grendel fanboys yap about are designed for high velocity rounds like the 6.5-.284, .264 Winchester, and similar rounds. The really light bullets suitable for use in the AR are varmint grade bullets. I don’t know of any 6.5 bullet designed specifically for hunting and/or self defense in the Grendel like those in the 90-120 gr. range used in the 6.8.

            When you compare the factory load selection between the two, the bolt breakage issues, loss of powder space when using heavy bullets due to magazine restrictions, etc., I see no advantage at all to the 6.5 based on the Russian case in an AR. When I bought my 6.8, it was my first AR, and that came after more than six months of research into all the available options. The 6.5 didn’t make the cut, and neither did the 5.56. 7 years later, I still think I made the right choice.

            I do own a 5.56 NATO 1:7 twist now, a .277 Wolverine wildcat, and soon a 7mm Valkyrie wildcat. All AR format. The Wolverine is a .277 on a 5.56 case, and can push a 90-100 gr. in the 2700-2800 range (and soon we’ll have 180 and 200 gr. subsonic), and the 7mm can push 120-160 gr. in the 2500-2900 range (that’s 7mm-08 territory). Still no 6.5, or .300 BO.

            So, all of the above is to illustrate that the 6.5’s biggest claim to fame is the BC at long range. At 300 yds and less, it has no advantage and even some disadvantage compared to similar sized rounds. IF I went with a 6.5, it would be the 6.5-6.8. Better ballistics and none of the mechanical issues of the Grendel.

          • I’ve been doing analyses on 200m optimized round for the past month; BC absolutely is relevant at those distances.

            You don’t seem to know very much about the 6.5 Grendel, because it has an excellent hunting bullet selection in the 107-130gr weight class.

          • Mad_Gorilla

            You were the one who tried to compare the 6.8 into a long range hole to compare it to the 6.5, not me. It wasn’t designed for that. Also, if I remember correctly, the Grendel case has less capacity than the 6.8, so those longer bullets are going to restrict powder capacity. And, those bullets were not designed specifically for the 6.5 Grendel as I said. The 6.8 has purpose designed bullets for hunting from 85 gr. to 120 gr, So, restrict the 6.5 to 300-350 yds where the 6.8 SPC II is intended to be used, and make your case. You’ll find the 6.5 isn’t any better.

          • No, the 6.8mm SPC was designed for the Mk. 12 SPR. So the person who put the 6.8mm into a designated marksman role was… The folks who designed it.

            They have about the same capacity. The 6.5 Grendel also has purpose designed hunting bullets in a wider weight range than that (85-144grs). So I’m not sure I see your point.

            But anyway, here’s the 6.8 and 6.5mm compared, with some additional notes below:





            Some things to notice: First, the 6.5 Grendel becomes faster than the 6.8 SPC at 250 yards, despite having a heavier bullet. Second, by a mere 90 yards, the 6.5 Grendel has retained more energy. So much for claims that its BC wouldn’t matter under 300 yards!

            And of course, it’s long-range performance just embarrasses the 6.8 SPC.

          • Mad_Gorilla

            First, what they do at 500 yds is immaterial. Even your own graph shows they are nearly identical at normal hunting ranges. When you’re still inside the point blank range window, worrying about a fraction of an inch one way or the other is absurd. And, I’m throwing a flag on the bullets. Give me proof that anything over about 120 gr in 6.5 was designed specifically for the Grendel. I know better.

          • The 123gr Sierra MatchKing was designed specifically for the Grendel, as was the 120gr Norma. What the bullets were designed for also does not matter, as the 6.5 Grendel can be loaded with them just fine. Here’s proof:





            I do not know why it is so difficult for you to accept that a cartridge with a much longer ogive would be able to accept heavier bullets and that it would retain its performance better.

            Why do you think a 107gr Scenar would make these graphs go any better for the 6.8mm? It would have only 40 ft/s less velocity, and still have a much higher BC.

          • Mad_Gorilla

            Except that if you’re going to compare two cartridges, you have to compare them at the same pressure level, and using bullets of the same weight and purpose. Comparing SPC I factory ammo with hunting bullets to higher pressure Grendel ammo loaded with match grade bullets is disingenuous, if not an outright attempt to cook the numbers. That’s why your reputation as an honest writer isn’t so hot.

          • LilWolfy

            6.5 Grendel case capacity = 35gr H2O
            6.8 SPC case capacity = 34.8gr H2O

            The 6.8×43 was born during SOCOM’s Enhanced Rifle Cartridge initiative, which was primarily looking at a Designated Marksman load. There was also an attempt to demonstrate a complimentary carbine profile weapon, but a lot of the original guns were 18″ barreled DMR type sticks. Many people thought the choice to go with a .277″ was really odd, and defied logic really.

            The 6.5 Grendel was designed around the existing 6.5mm bullets on the market. It didn’t need any special projectiles for it. This constant claim otherwise is simply false, and ignorant of the various legacy military 6.5mm projectiles, as well as the hunting projectiles that naturally followed in the 20th Century. All of those cartridges were lower pressure military rounds with moderate muzzle velocities.

            The first one to break that mold was the .264 Win Mag, but it didn’t drive hunting bullet production like the 6.5×55 did, and was discontinued from Winchester’s factory rifle line-up. Repeating this mantra that .264 Win Mag and 6.5-284, or even .260 Rem is what 6.5mm bullets are designed for is contrary to reality. When presented with the facts, I notice that you double down on these statements. Why is that, exactly? Just curious. Are you getting your information from some unknown source that knows something everyone else doesn’t?

          • Marc

            At 300 m or less 5.56 will do just fine. It’s well beyond that range where an upgrade becomes necessary, BC becomes very relevant and 6.8 fails to deliver – just like the whole article says.

          • Mad_Gorilla

            Not what the guys I’ve talked to who have been in the sandbox. In any case, the possibility of the military switching to the 6.8 (why it was created in the first place) is long past; that ship has sailed. The people like Harrison at ARP picked it up and turned into a premier h;unting round for the AR. Why the author tried to hang it with the military stuff only to shoot it down for Remington’s screw ups is what is disingenuous. None of the 6.5 guys want to compare apples to apples, and haven’t for years because they lose every time. I’m done.

          • Denial.

          • LilWolfy

            Which bullets are designed for the 6.5-284 and .264 Winchester Magnum again? Maybe the Barnes 130gr TSX. The Barnes 120gr TSX fits well within the 6.5 Grendel, and is a known and consistent performer on medium and large game-has been since it was introduced as a factory round.

            Your claims are way off the mark so far. One of the only bullets I can think of that might have been made to meet the demands of the 6.5-284 is the 142gr Sierra Match King target bullet.

            There is a very long list of projectiles that work exceptionally well in the 6.5 Grendel, and those are primarily in the 85-130gr weight range, with a few exceptions. The 6.5×6.8 does not have better ballistics either, and is a less efficient case. It takes 2 grains more powder compressed into the case to do what not even a max load in the Grendel does, and does not have the room to play with when looking at ogives. Trying to catch up to the Grendel with a higher pressure approach will fail every time in the AR15 dimensions.

    • ConservativeSurge

      Nailed it.

    • The figures used are representative of performance attained from SSA ammunition from 18″ barrels.

      • Mad_Gorilla

        SSA is out of business. Their ammo wasn’t that great anyway. Problems with primers, pressure, etc. The best rifling twist for performance is 11.25:1, and the best rifling is 5R. Top loads are running between 55k and 60k pressure.

        • SSA is not out of business, so far as I know. Their website has moved to Shooter’s Pro Shop.

          I feel that report I linked is a very good overview of SSA ammunition. Regardless of the ammunition’s quality, it appears to be very indicative of the practical performance possible from the 6.8mm SPC.

          • Mad_Gorilla

            Nosler bought SSA. Any SSA ammo being sold by SPS is left over SSA stock. But like I said, SSA had lots of problems with pierced primers, their Tac loads were often loaded too hot, and their brass had hardness issues. Rest assured that any new stock will be loaded by Nosler, even if it is sold under the SSA banner.

          • Which isn’t the same as being out of business…

            I agree about their ammo being very hot.

          • Mad_Gorilla

            Not the same people building it, not the same components, not the same lousy QC, etc. They basically bought a name, and nothing else.

          • Does this mean I should keep my 6.8 performance figures well below SSA’s numbers? 😉

          • LilWolfy

            You could use the old SSA loads. They had:

            ..or something along those lines.

            Too bad someone like Nosler had to come along and hold all the loads to the same working pressures to appease some silly legal department. Nosler, what amateurs. If only SSA had stayed in business and continued to deliver their tiered performance loadings for the ultimate experience in 6.8 superiority over these silly other cartridges.

          • I used SSA loads from 2008. 🙂

    • Don Ward

      Strangely enough, 2002 also thinks that Nickelback is awesome, considering how much 2002 loves the song “How You Remind Me”.

      I wouldn’t take what 2002 has to say very seriously.

    • MarylandShooter

      LOL, my guess is he’s used to it by now.

    • Gunther Fischbach

      Eeyup, he’s embarassing himself like mad. Just look at all the comments calling him out. And all he does is say ;Th47z l13k t0te5 n0t wut i s3d g14z!!111!!!!!!1111!1″

  • brian

    I would not consider the 115 matchking or 110 hpbt as ball rounds. Federals 90 gold dot is the new standard ball round, developed specifically for MIL in mind.

    • That round has even worse ballistics, though the bullet is a reasonable design.

  • ConservativeSurge

    “Detractors point out that the round fails to fragment when the striking velocity is too low…”
    That’s a straw man, as the issue is the M855 doesn’t fragment at all, even at “high speed.” 6.8 was meant to solve the “ice pick” problem of M855 out to 300 meters.

    • It’s not a strawman, as that exact issue (fragmentation threshold) has been brought up many times.

      Even so, how does the 6.8mm SPC solve the fleet yaw problem? I have yet to receive a satisfactory answer on this, despite asking several times.

  • DPrahl

    Nate my man you need to research your rounds a little better before putting your opinions out in the open. Please review what is now the standard and has been for a while now, 6.8 SPC II chamberings. The 6.8 SPC was dead in the water as soon as Remington screwed up the specs. Of course performance suffered when the requested chamber was speced wrong, but the rest of us know that’s all history.

    • The performance figures used represent 6.8 SPC Spec II and 6.8 DMR chambers.

      • DPrahl

        Then I guess I’m a ballistics genius because my 6.8 rifles show a lot more performance in FPS and accuracy than your article suggests the round is capable of.

  • Don Ward

    So in other words, time to adopt the 30-30 as the next GPC like I’ve been saying all along!

  • Capt Grumpy

    WOW! Are you a democrat from California or do you write their stuff? And your YUGO can outperform my Porsche! Your journalism teacher (if you ever had one) would like to put you back in detention! A village somewhere is looking for their lost idiot!

    • Kevin Harron

      I’m not high enough to comprehend Nathaniel being a democrat from California. Need more weed.

    • Don Ward

      I have it on good authority Nathaniel consorts with known Communists. I have exactly 57 different documents proving this.

  • Nathaniel amazing article! Very rare to find info this detailed.

    Have you heard of a round called the .375 Reaper? It’s a 300 blk but in a chopped .308 case and uses a .375 bullet. Interesting design and was featured on TFB. I’d like to hear your input on it

    • For the purpose of flinging very heavy bullets very slowly, it seems just fine. 🙂

    • Brandon

      As niche as niche can get. Special bolts, uncommon cans. So slow the heavy jacket bullets would never expand. Absolutely worthless for mil use, ammo is heavier than current ammo while they are trying to lighten ammo by 20% and increase range if conflicts continue in the middle east.

    • scotchflavoredchewablevicoden

      What does it do that say…. .45 ACP won’t do?

      • iksnilol

        Range, pistol bullets aren’t the most aerodynamic ones.

        • In the subsonic flight regime, spitzers don’t have that much of an advantage. They all drop like a rock, and have the terminal performance of a hearth poker.

          • iksnilol

            There must be some advantage, otherwise we would just use .45 acp carbines and be done with it. Maybe the extra weight of the projectile helps with velocity retention? I know I read that .510 whisper loses very little velocity out to 500 meters or something.

          • .300 Blackout is a much easier AR conversion than .45; that’s the primary reason it’s more popular. It’s also a little more versatile (though not as much as its proponents say, I think) as there’s the potential for decent supersonic ammunition, as well.

            Things like the .338 Spectre, .375 Reaper, etc are not very popular.

          • iksnilol

            But doesn’t it have better trajectory than .45 acp? I am just curious.

            Also, I don’t know how assassins in America operate but in Europe everyone uses stuff like .338 spectre and .375 reaper. The American calibers are extra popular because then we can blame it on you guys.

          • Based on my analysis of subsonic .300 Blackout that I did a while back, the trajectory difference isn’t anywhere near what you’d expect. This makes sense as the primary factor in flat-shooting rounds is high velocity.

  • Giolli Joker

    I’ll try to spend some time in understanding and analyzing the article and the discussion it has sparked, it looks definitely interesting.
    However, with a quick glance, I’ve seen a mix of units of measure that makes me cringe a bit.. for future use I’d suggest to either stick with one standard or to use both in parallel, I think it would help the reader.

    • All I can say is… Welcome to small arms. 🙂

      • Giolli Joker

        I have quite a few book on small arms as well… although I admit I haven’t studied them as deeply as you did, I don’t think I’ve found inches and meters in the same graph, to say one example…
        It’s a messed up world, you can make the difference starting from the small details. 😉

        • In Europe it’s a lot more consistent. In the United States, the units get very mixed up. For example, I used meters because the meter is the standard unit of measure for range in the US military. However, feet per second is still the standard unit of measure for velocity of US military ammunition.

          Like I said, all kinds of fun.

  • iksnilol

    I never understood 6.8 SPC, the 6.5 Grendel does everything it does but it has longer range. + it uses 6.5mm bullets which are easier to find than 6.8mm bullets.

    I mean if you are going to do the “AR in uncommon and expensive caliber” at least do it right and get the most benefits out of it.

    • I’m no 6.5 Grendel fan, but yeah, I don’t see the attraction of 6.8mm versus the 6.5mm.

      • Dan

        100pts if you change the article to 22lr better than 6.8mm SPC

    • Mad_Gorilla

      Except the 6.5 has a lousy selection of hunting bullets, and the 7.62×39 based bolt for the 6.5 breaks a lot. The Grendel fan boys hate when the truth is told. The 6.8 is the #2 selling cartridge in the AR, and #1 for hunting. One of the better AR barrel makers no longer offers barrels and bolts for the 7.62×39 or the 6.5 Grendel because of breakage issues.

      • Uh…

        I don’t normally defend the 6.5 Grendel, but it’s capable of using almost all 6.5mm bullets compatible with .260 and 6.5mm Swede.

        6.8 SPC in contrast uses a totally new bullet profile versus the .270 Winchester.

        • toms

          6.8 is the second most sold AR caliber after 5.56. That’s common industry knowledge.

          • I have a hard time believing that without a source.

          • MountainKelly

            This discussion went places.

          • toms

            The last concrete source I can think of is when ATK announced 6.8 spc production a couple of years back. “to take advantage of the second most popular AR caliber ATK announces that it will be producing 6.8 spc ammunition ect ect”. Not bothering to find a link because I don’t care really. 5,45 and 22 aren’t AR specific calibers, not really hard to figure out if you think about it. 6.8 has been around a lot longer than blackout which is probably more popular right now, but its got a ways to catch up in numbers.

          • scotchflavoredchewablevicoden

            I’d be interested in seeing a source for this.

          • scotchflavoredchewablevicoden

            So…. No sources, then?

        • Mad_Gorilla

          The best factory load for hog hunting with the 6.8 is the 120 gr. Hornady load. You can do even better with handloads and that bullet. The problem with 6.5 bullets is that in order to have sufficient weight the length of the bullet is excessive for the caliber. That causes them to rivet and fail when heavy bones and gristle are encountered. The militaries of the world discovered that fact 100 years ago. That’s when almost everybody dropped the 6.5 in favor of larger calibers. Those long bullets also eat up powder space in the smaller capacity cases used in the AR format.

          • Comparing modern hunting bullets with military round-nosed FMJ bullets from a century ago is disingenuous and misleading.

            I don’t see how a .264″ projectile of a given design would be any less effective than a projectile thirteen thousandths of an inch wider.

          • Mad_Gorilla

            It is not disingenuous or misleading. Nearly every military dropped the 6.5 in favor of something in the .30 caliber range. 6.5 just wasn’t effective on the battlefield. When everybody went to spitzers in the mid-20’s, the 6.5s couldn’t compete because the bullets were too light after the change to spitzer. And that was in cases about the same size as the .308. Put a 6.5 in an a case that only has half the powder of the .308, and you still have the same issues. And yes, .013″ does make a difference. Everybody rants about BC, but I’ll take a lower BC better balanced bullet over a long skinny high BC any day.

          • Tell me more about how .013″ turns a bullet from Ineffective to Effective.

          • Kivaari

            The failure of the 6.5mm rifles was the use of round nosed heavy bullets. Had they used modern projectile it wound have performed much better. The very long ~160 grain bullets are very stable and don’t upset fast. The Italians tried introducing the 7.35mm having a light aluminum nose insert that made the bullet tumble. They did that in 1938, and was too late to make the switch. The Brits did it sooner with the .303 Mk7 for the same reason. Like the US going from the M1903 bullet to the M1906 bullet. Killing effect increased dramatically.

          • Kivaari

            Is that why so many of the famous ivory hunters killed so many elephant with 6.5mm M-S rifles? They used what were ineffective bullet designs in 6.5mm, 275 (7mm), .303 and .318. The ammo they had was military round nose, that in combat against men, killed lots of critters that needed deep penetration. Some of the most successful hunters loved the 10 shot .303 No1Mk1 rifles.

          • Dual sport

            This was supposedly a wide spread practice. There may be new information that says this was not as widespread as many wrote, thought, or interpreted.

          • LilWolfy

            WDM Bell’s preferred cartridge and rifle for most African game was the 6.5×54 Mannlicher Shoenauer, which is the ballistic equivalent of the 6.5 Grendel from the muzzle.

            He did harvest some of the over 1100 elephants with it, but from all I’ve read, he used the 7×57 Mauser and .303 Enfield for the majority of his elephant hunting.

            When it came to Giraffe, Kudu, Warthogs, Impala, Gemsbok, etc., he used the 6.5×54 M-S. Take a look at those animal profiles and see what game size/construction we’re talking about, then consider that he was using a legacy steel alloy action, with lower pressure loads. Hard to argue with a guy who killed over 1100 elephants and who knows how many African large and medium game in order to pay local tribal kings for intel on where the elephant herds were.

          • All the Raindrops

            It’s more effective because it more closely mimics the perfect shape for transonic flight shown in the wiki link in this article. 6.5g has a better B.C. than anything mentioned thus far.

          • Kivaari

            Dr. Fackler did tests on the 6.5mm Carcano to see if an Italian army doctors testing circa 1900 would hold up using modern techniques. What the US Army found was the Italian study was exceptionally accurate. In the gel block tests Fackler showed that the Carcano round was the deepest penetrating round his laboratory had tested.
            Some where I have a letter from Dr. Fackler along with a photo giving the results. It was impressive. I have contended for years that a 6.5mm Carcano loaded with a better bullet was just about an ideal military round.

          • Kivaari

            Exactly. That wonderful bore diameter of the 6.5mm (.264-268) given a proper bullet will do anything needed in both hunting and military contexts. There was never anything wrong with the post-1890 caliber rifles once bullet designs came along and improved the terminal performance. All the armies learned a spritzer boat tail or flat-based bullet out performed the long round nosed bullets. In the air the modern bullets flew farther than the heavy round nose. In tissue, since deep penetration wasn’t an asset, the spritzers gave quicker and significantly worse wounding effect. If a hunter wanted deep penetration, they gave up long range performance for deep penetration in game. It is why the well known “Great White Hunters” of the 1890’s to 19-teens used old pattern military ammo to take huge game with close range shots. One thing they knew was don’t take shots from hundreds of meters away. Get in close and put the bullet precisely where it needs to go. When using a .264-.318 diameter bullet on elephant you need to be very close. A “good hunting bullet” by our standards would have been the wrong bullet for them. Old time deer hunters knew the bullets of the pre-WW2 era being soft point versions of the old military rounds simply killed better than the pointed soft points. It is one reason sales of 180-220 gr. .30 caliber ammo was so popular. Even Elmer Keith noted that they were better in a military setting. While he worked at one of the arsenals in WW2 they found the flat based .30-06 bullets killed better than the boat tailed rounds. Flat based tumble quicker but give up range compared to boat tails. It’s only been in the last 40 years that truly new designs using new materials has changed performance.

          • “That’s when almost everybody dropped the 6.5 in favor of larger calibers.”

            Those were the days when battle rifles ruled. Those days ended many decades ago.

            “Those long bullets also eat up powder space in the smaller capacity cases used in the AR format.”

            You can get better external ballistics and range by moving outside of the AR-15 format, but that’s obvious, isn’t it?

            If you’re going to argue that bigger is better, then there are 7.62mm short cartridges and larger that will fit in an AR-15 magazine well, but then you’re going to have to deal with some extreme drop at longer ranges.

            For military use, the weight a combat load is also an issue. There is a point at which the drawbacks of a heavier bullet outweight the benefits, pun not intended.

          • Kivaari

            Those bullets were made for the many other 6.5mm caliber rifles. All the 6.5mm military rounds, that only had case neck length differences, all using the same case diameter as the 6.5 M-S/Carcano, even though the Carcano was actually a .268 diameter bullet. Since all of them carried more powder they could do better. Insert the 6.5x55mm Swede and now you have a much more powerful cartridge for military or hunting. The Swedes did issue an 8mm rifle that fired a very heavy loads in a tripod mounted machine gun. The gun crews used the rifle in the same hard kicking load. The Japs used several 7.7mm rounds including the .303 British in a Japanese ripoff of the Lewis gun, and a 7.7mm semi-rimmed round intended for use in a machinegun, but unsuitable for the similar rifle.
            The Brits also issues 7.92mm machineguns in vehicle mount uses.

        • Dan

          I’m going to have to ask for a source for it at the #1 hunting spot

      • scotchflavoredchewablevicoden

        Having shot the 6.5×55 Swede for around 20 years, I’m going to call BS on the whole “poor selection of hunting bullets” thing.

        • Brandon

          Do any of those bullets expand at the slower velocity that the Grendel can produce given they were designed for the 6.5×55 and 260 Remington?

          • Yes; many of them do. The TSX, for one.

          • Brandon

            Shoot those bullets into gel at 300 yds instead of 10ft from the muzzle and let me know what they look like. I could save you some time but it looks like you need to real first hand experience.

          • You must not do much hunting if you think 300 yard shots are common.

            But anyway, at 300m, the 6.5mm Grendel will be going faster than the 6.8 SPC.

          • n0truscotsman

            Its the internet. You know damn well the “snipers” on the interwebs are capable of 1000 yard 30-06 shots with a one inch holdover. 😉

          • iksnilol

            But you forget that 6.8 SPC has a 3mm wider bullet!


          • *0.3mm

          • iksnilol

            Yeah, but it is special (says so in the name). So presumably those 0.3 mm become multiplied by 10.

          • Kivaari

            That’s like those saying the .40 S&W is so much more than the 9mm.
            The 1mm increase in diameter doesn’t mean anything. If you look at the permanent wound tracks of FMJ bullets in, .38 Spl. (9x29mmR), 9x19mm, .45 ACP (11.25mm) and rifle rounds, like 7.62x39mm and 7.62x51mm the wounds are indistinguishable. The REAL world of gun shot wounds in tissue like an arm or leg w/o bone interaction, leaves a wound so similar that a surgeon can’t tell you what caused it. Shooting a Philippine Insurrectionist 110 years ago with a .30 US rifle left a neat hole. A wound that could heal enough in 2 weeks that a man could rejoin his company. That was in lung or extremity hits, with no entry wound bone being hit. Our ancestor’s from that era were not ignorant of what bullets did. Some nations simply did not modernize rifle bullets designed in the 1890s. Even in 1900 the Italian Army knew the FMJ-RN bullets they issued were not ideal. They knew a modern pointed boat tail bullet was better then the FMJ-RN.
            Even knowing that, they found the rifles did pretty much what was needed. In WW2 the Finns re-chambered most of their service rifles to use the heavier “D” load from the Soviet supplies. The Soviets used the “D” – long range loads in machineguns. With a slight turn of a chambering reamer the standard Mosin-Negant rifles M91 to M39 were marked “D” and made good use of that ammunition. It added a few hundred meters to the effective range. Had they kept very old heavy round nosed bullets they would have lost hundreds of meters. The Russians found in 1905 that the original RN loads performed poorly in the war with Japan. That’s when they switched to a 147 gr. flat based load for rifles and the “D” round for machineguns. The flat based bullets were more effective against human targets. Same for Yugoslavia going from the Soviet style M43-PS bullet to a flat based load. They killed better than the M43-PS. Bullet shape really effects range and wounding. Adding a light metal or fiber insert in the nose of a bullet increases its wounding effect. That “AP” core in the M855 isn’t there for its penetration. The 5.56mm needs that yaw, to cause it to yaw and rip a new one on the host.

          • iksnilol

            I was being sarcastic.

            The “/sarc” at the end of the message signifies sarcasm.

          • Kivaari

            I was replying to the string of comments, not your single comment, which had the wrong math, but made a similar point.

          • iksnilol

            ah, makes sense. Yeah, I messed up. Typing error, super embarrassing that I wrote 3mm instead of 0.3mm but I believe I managed to save it nicely.

          • Kivaari

            Everyone knew it was simple and very human error. It didn’t bother anyone, as everyone knew your intent. The point being bullet diameter has little impact on performance. Shape gives us increased range. Shape effects wounding. Finding the balance within the confines of what is allowed in international combat is the key. If you look at the VLD bullets, and view them without a known reference size, you really can’t tell a .22 from a .338. The very developed aerodynamic profile translates to all calibers. It is why we can use OTM ammo to kill the enemy, where in the past it was an “accepted fact” that hollow points were unlawful. We also know that the OTM .308 168 gr. bullet used by military and law enforcement is less effective in shooting men, than a 165 gr soft point Sierra Gameking is a much better bullet when you are shooting man or beast.

          • Brandon

            So you talk about the long range ballistics of the 5.56 being better than the 6.8 and the 6.5 being better than the 6.8 but then when I say shoot the 6.5 bullets (designed for the sweed and 260)at range out of a Grendel to see how they expand you say “who shoots over 100 yds” That is funny. If you only shoot 100yds the 6.8 has better terminal performance than the 5.56 or 6.5.
            First deer I ever shot in the late 70s was across a cornfield almost 200yds. 3-400 is common down power lines and cuts, over fields. The last trip to Texas we hunted a farm that was over 3000 acres of corn. We could have taken 600-800 yard shots.

          • Marc

            Long range external ballistics of a military cartridge and the range hunting bullets are used at are two completly different topics. Deer don’t shoot back.

          • No, I said the 6.5 Grendel will have better performance at 300 yards than the 6.8mm (which is obvious).

            Hunting is best done at ranges between 50-200m, to ensure an accurate, humane hit. I never said the 6.8mm was a poor hunting round.

          • Mad_Gorilla

            I’ll put the .277 Wolverine up against the 6.8 and the 6.5 G out to .300 yds with no problems. MOA accuracy or better, and we’ve got the proof of animals taken with it this last deer season. Your 6.5 isn’t quite as good as you think it is. Btw, I know of at least one elk that was taken with the 6.8 and over 350 yds. One shot, dead right there. I’ve seen the picture. There’s also a series of pictures of a Kodiak brown bear taken with the 6.8 in a Mini-14 that’s been on the ‘net for at least 3-4 years.

            Point being, you saying the 6.5 Grendel is better than the 6.8 is obvious is anything but obvious especially when there are other rounds that do just as well with even less powder.

            I’ve written articles and had them published as well, so I know how the process works. Some of us do it without pulling the wool over reader’s eyes, and without creating straw men to knock down to make their points.

          • Kivaari

            I think the point is the 6.5 has more bullets having a combination of shape and weight, outperform the 6.8 that has a smaller selection of bullets, none of which hold up in flight as the 6.5. Going from a 100 grain .264 bullets gives the shooter a better profile than a 100 .277 diameter bullet. That makes the 6.5 fly better and retain energy better.
            Hitting a deer with either one at 300m simply wont show differences that can be proven in a scientific manner. But showing flight characteristics is a provable subject. Launch the same weight bullet at the same velocity and the smaller diameter and longer bullet will be better. There just isn’t a way, I know of, that give the same low drag bullet shapes that fit into an AR. It is why the 6.5s have held up well in competition.
            If I remember right the 5.56mm with proper loads has beaten all the records previously held by the 7.62mm NATO. When they are launched at the same velocity the one having a better low drag bullet contour will win.
            About 15 years a go a friend won a 1000 yard match using a Savage M112V in .308 with a Simmons 15x scope shimmed with two layers of 7Up plastic. He used 165 gr Sierra GAME King bullets that left keyholes in the target. It was written up in the news letter for the American Special Snipers Association (can’t remember the exact name. He is Kino Davis. He was sent to Great Lakes Camp Perry to teach, he was in the USCG Law Enforcement training section. Good shooters can do a lot.

          • Dual sport

            You’re relying on photos and descriptions posted on the Internet as proof of cartridge performance? Seriously?

          • Dan

            I was going to say, “I’ve seen the picture” how many times has that been said. Then the story comes out well, 350 we estimate and dead right there means he ran 300yds and then finally dropped

          • Mad_Gorilla

            I own a .277 and a 6.8. I’m fully aware of what each is capable of. You don’t know what the hell you’re talking about.

          • LilWolfy

            That was a hand-loaded round by a 6.8 barrel manufacturer who pushes the pressure limitations, and used a 20″ barrel. The animal was a small cow, which are about the size of mulies in many cases.

            The 6.5 Grendel has been used to take large bull elk at over 400yds with a factory 120gr TSX load, not a hot hand load. It has been used to take large deer at over 500yds, and large caribou at 400yds, using factory 123gr SST. Those are exceptional shots made by marksmen who train more than the average deer season shooter, but the capability is real regardless.

            The fact is, there isn’t anything terminal performance-wise or external ballistic-wise that the 6.8 can do, that the Grendel can’t, leading again to the question: “Why by a 6.8 when you can step into something with more capability?”

          • Mad_Gorilla

            6.8 factory loads are not loaded to the full potential of the cartridge because of all the original SPC I barrels out there. That’s because Remington screwed the pooch on chamber dimensions. Take a SPC II chamber that has the correct dimensions, and load the round to the same level the Grendel runs at, and there is no difference whatsoever over hunting ranges. That’s what the 6.8 excels at. If I wanted a cartridge for busting paper at 600 yds, I might consider the Grendel. But it has other issues that knock it out of the box, like bolt breakage because of the AK type bolt face.

            Btw, there was a picture of a large cow elk taken with the 6.8 at around 375 yds if memory serves, that was floating around on the 68forum for a long time. I don’t remember the load used, but this was several years ago, so it was probably one of the 110 gr. loads.

            The biggest beef I’ve got with the 6.5 fans is that they usually aren’t willing to have a discussion when all the facts and parameters line up like for like. The 6.5 Grendel fanboys have been lying for years about what the 6.8 is capable of doing. Anybody can reel off stats based on ideal conditions, but paper stats don’t mean diddly. Real world use is what counts, and there is more than enough data out there to establish the bona fides of the 6.8. That’s why I said I’d take the .277 Wolverine over both the 6.8 and the 6.5 G., and the .300 BO. It is so efficient that it can cover the heavy bullet suppressed end, and all the way up to large medium game at 350 yds going supersonic. All that’s required is a barrel change, everything else is box stock 5.56. It runs 85 gr. to 200 gr. without batting an eye, at 1000 fps for the 200, up to 3000 for the 85. Neither the .300, 6.5, or the 6.8 can do that.

          • LilWolfy

            6.8 ammo factory ammo is not loaded to higher pressures because the AR15 action can’t take sustained firing schedules at those pressures with less chamber wall thickness than 5.56 NATO, especially with a lot of the steels being commonly used.

            The SAAMI spec chambers are only one consideration. Even if the SAAMI chamber had never been loused up the way it was, and the original Murray or DMR chamber had been used, you still need a sensible pressure-rated vessel and cartridge loading approach that limits the pressures. The AR15 diameters and .421″ case determine that, regardless of throat geometry.

            It also doesn’t help promote a cartridge in the long run by attacking the character and integrity of other gun owners who happen to find another cartridge to their liking, by calling them liars. This is really the worst aspect of the 6.8, where personal attacks and accusations of lying or misrepresentation of the facts are constantly made when the technical and real-world performance of other cartridges show better results. That was the immediate course of action after the Blackwater shoot in 2004, when the Grendel was publicly demonstrated, which is a loser’s way of admitting defeat, by lashing out at a better product.

            That kind of marketing will only last for so long, and people will start to see through it, and want nothing to do with it unless they have that type of personality.

          • Mad_Gorilla

            That’s an outright lie. There are any number of cartridges that are bigger than the 6.8 that run in the AR15 format without any problems with pressures. As far as attacking other gun owners goes, the 6.8 users didn’t initiate that crap, it was the Grendel and Blackout owners who did that. I’ve been following this for a long time, so don’t try to bamboozle me with your fanboy crap.

            Try asking Harrison at AR15 Performance about how well his ARP 6.8 barrels hold up compared to other barrels. Ask him why he doesn’t chamber for the 6.5 Grendel. Get some real world facts for a change.

          • Mad_Gorilla

            Out of a 16″ barrel? I don’t think so. At best, about the same. We’re talking fractions of an inch here in terms of trajectory.

          • You often make claims like this while supplying no data of your own.

          • LilWolfy

            The best comparison between the two is the 6.8 120gr SST versus the 6.5 123gr SST. Factory ammo produces the same muzzle velocities from 16″ carbines. The Grendel is exceeding 6.8 from the muzzle at academic numbers, and then slowly out-gasses it as the distance increases. This is for hunting applications. You’re looking at a G1 BC of .400 for the 120gr SST, and in the .462-.510 region for the 123gr SST. The 123gr SST consistently expands down to 1800fps.

            You can then turn around and shoot one of the scores of efficient target bullets for ringing steel at distance with a trajectory like a .308 Win. For me as a customer, that’s what made me choose the 6.5 Grendel over the 6.8 SPC. The question will be asked, “Why would I choose one that only has partial capability, while the other has both?”

          • LilWolfy

            The 120gr TSX has been used to kill large bull elk at over 400yds from a 20″ barrel, factory load. It’s a known fast killer on medium and large game. At Grendel velocities, it penetrates extremely well because impact speed isn’t too fast, nor too slow until you push out beyond what most hunters are capable of, and even then, you’re getting a pass-through at least.

            The performance envelope between the 6.5 Grendel and other legacy 6.5 military rifles isn’t different enough to require a complete bullet selection redesign, like what was necessary for the 6.8 SPC.

          • uisconfruzed

            Berger’s work great in mine.

          • scotchflavoredchewablevicoden

            Having recovered them in game at ranges between 350-500 yards, I’d say “absolutely”. 6.5×55 isn’t exactly a barrel burner, you know…

          • Kivaari

            It is why the 6.5x55mm is still very popular for “elk” (moose) hunting in Scandinavia. The “ineffective” 6.5mm loads said to have been taken out of service by the worlds militaries can’t be any good. Odd, why it still works so well when everyone knows it is not good enough to kill men. The 6.5x55mm is one of the best cartridges ever produced.

          • LilWolfy

            There are over 80 different hunting-specific 6.5mm projectiles on the market, and the claim that they were made for the .260 Remington falls short of reality, since the .260 Rem wasn’t SAAMI-specified until 1997. Remington doesn’t support any of their cartridges like that, especially the .260. The 6.5×55 Mauser is only one of the legacy 6.5mm cartridges, along with the 6.5×52 Carcano, 6.5×54 Mannlicher Schönauer, and 6.5×50 Arisaka. The 3 latter cartidges are about ballistic equals to the 6.5 Grendel, since the Grendel operates up to 50,000psi, with the advantage of modern steels.

            So yes, the vast array of 6.5mm projectiles expand reliably over common hunting distances for medium and large game when shot from even 16″ 6.5 Grendel carbines. Some have lower expansion thresholds than others, but these don’t come into play until past 300yds in most cases. The 120gr Barnes TSX, for example, is a solid killer from the Grendel, producing fast kills on hogs, mulies, and elk.

            The 6.5 Grendel has superior hunting performance to the 6.8 SPC for many of the reasons stated in the article, starting with the available ogive length and resulting BC and SD, and is regularly used to take mule deer, and more and more elk as people discover what it is capable of. It is a surprisingly efficient cartridge, with very little recoil.

      • n0truscotsman

        You mean the number 1 caliber_in ARs_for hunting?

        Because there is no way in hell its number 1 in hunting total. It would have to get in line behind 30-06, 308, .270 win, 45-70, and anything else in between.

        Number 2 is questionable too. There are a lot of 308 caliber AR10s being sold and 7.62x39mm ones.

        • Nicks87

          Exactly, I can walk into the local gun shop right now and find several .223/5.56 and .308 AR rifles on the shelf. I cant remember the last time I saw a rifle in 6.8 SPC.

          • Kivaari

            I’ve only seen one in a store and it was a Remington M700. I would have probably bought a Ruger in 6.8, but none ever showed up in the area.

          • Dan

            If you do find one i can find you the ammo, sitting on the shelves covered in dust because no one buys it.

      • iksnilol

        6.5mm and lousy selection of hunting bullets? That statement might hurt your credibility a bit.


    • Brandon

      He talks about weak bolts and keeping the pressure down. The Grendel bolt is weaker than the 6.8 bolt.

      • The 6.5 Grendel and 6.8 SPC produce about the same bolt thrust given factory pressures. The 6.5mm is about 6,000 PSI more limited than the 6.8mm.

        • Brandon

          Same bolt thrust but the lugs are weaker on the 6.5 due to a thinner backing rim that the bolt is attached to. Take them to a simple lab and have a shear test done.

          • I wasn’t disagreeing. I make the same point about bolt thrust in the article.

          • Coolhand77

            perhaps a compromise? Say a 6.8 SPC case shortened to take the better 6.5 projectiles? Ups the case capacity over doing the same thing to the 5.56×45 case, reduces the bolt thrust over the 6.5 grendel case, and allows the use of the higher BC/SD, more common projectiles…oh, and allows for a stronger lug on the bolt.
            Another thought, rebated rim like the .50 beowulf, only scaled down to put the smaller 5.56 case head on the new, wider cartridge…it would allow for stronger lugs, how would that effect bolt thrust?

          • LilWolfy

            Not enough ogive length. Been tried already.

          • All the Raindrops

            They are making dedicated 6.5G bolts with thicker backing now.

            6.5 is a better performer at 1000 yards than .308… out of AR15 mag length. that is very impressive.

          • Brandon

            Only if you use Lapua bullets in the G and 175gr military loads in the 308. Lets keep this apple to apple here for a litle bit of truth. As for the thicker backing…how? the outside dia has a spec, the inside can’t be smaller than the case. Measure the bolts yourself and then think about that one.

          • Brandon, he’s talking about Alexander Arms bolts that have a more shallow bolt face. That strengthens the bolt considerably; it’s been that way for years.

          • 6.5 is a better performer at 1,000 than some .308 – M118LR still licks it, for example.

        • LilWolfy

          6.8 SPC should only have maybe 2,000psi more when looking at the MAP if you run the numbers yourself. It wasn’t handled very well at all during the SAAMI submission process. The idea that MAP can increase 6,000 psi between a case that is .421″ at the base, versus one that is .444″, has never worked when I’ve run the numbers for both Bolt Thrust and Hoop Stress.

          Not only was the neck-to-freebore angle done horribly, but the FOS and pressure ratings are beyond realistic given the limitations of the AR15 frame and barrel dimensions.

          MAP should really be maybe 52,500psi for 6.8 SPC, and 50,000psi for the Grendel. Manufacturers are not going to load beyond that like SSA did with the “Combat”, “Extreme”, and “Tactical” loads. Now that Nosler acquired SSA, a more sound and safe approach has been taken with the 6.8 factory SSA with one standard for MAP. Unfortunately, people think that is “handicapping” the 6.8, and then they head off to the bench to stuff as much AA2200 into their cases as possible, with Accurate Powder data showing published loads in the 58,500psi region.

          These problems have never been faced honestly by the civilian side for a number of reasons. For starters, has anybody other than JSOC done a pyramid test with no less than 10 guns and 100k rounds?

          • LilWolfy, this suggests that it’s possible I am using incorrect data in my bolt thrust calculations. Could you show me your calcs? If you don’t want to do so in a comment, you can always email me at

          • LilWolfy

            If you were using the listed SAAMI MAPs, then I suspect you ran the calcs correctly for a simple comparative analysis, but that is based on the assumption that the MAPs are good for both cartridges, which they aren’t. Neither of them are ideal due to hoop.

            Also notice how we never hear about broken 6.8 bolts, but 5.56 bolts break all the time. I’ve done it myself with 5.56. People aren’t shooting their guns in volume, and I doubt many manufacturers are running pyramid testing due to the simple fact that it costs a lot of money, and what do they do if the pyramid testing indicates a need to reevaluate things from the ground up since due diligence seems absent.

          • I would love to carry on these conversations via email, which is much more convenient for me. My email is in my author’s description.


      • iksnilol

        Grendel bolt issues were people running hotrodded loads that were above max pressure. That will mess up any gun. And the other issues were people using inferior 7.62×39 bolts in 6.5 Grendel.

        Not a fanboy, but I like the truth.

        • LilWolfy

          They are largely attributed to after-market bolts meant for the non-researched 7.62×39 AR15 bolts, many of which are 8620 steel that will often crack or shear lugs on 5.56 bolts after 300 rounds in a shooting course.

          Anybody that knows what they’re doing in the 6.5 Grendel barrel and bolt world, let alone 5.56 market, doesn’t use crappy metallurgy and weak bolts.

    • Dual sport

      I recall someone saying the military never warmed up to the Grendel b/c of the steep shoulder. It supposed.y did not like being ran in a bolt gun and the adoption was meant to result in the rechambering of many weapon systems.

      I don’t recall a source and don’t know how true that is.

      • Kivaari

        I think the military didn’t warm up to it, because it didn’t add anything that was a significant improvement over the 5.56. One thing we can say is the US military spends a great deal on research. There is no cost/advantage making any of those cartridges better. Performance beyond 300m really is not that important to the average soldier. If the enemy is encountered closer than
        300m, they have what they need to fight them. If the enemy is at greater distance, then we have mortars, air and arty support. Engaging the enemy at 200m, our men outshoot their men. Especially if they are using an AK.
        I suspect almost none of the AKs in use by our enemies has been zeroed.

  • Lance

    never cared for 6.8 SPC always thought 6.5 Grendel was a superior intermediate cartridge for those who hate 5.56mm and are too wimpy for 7.62x51mm. Don’t matter 5.56mm is here to stay.

  • Mad_Gorilla

    This guy is full of crap. The 6.8 will run rings around the 5.56 all day long. I own both, and have done extensive loading for both. The 6.8 is the premier AR cartridge for hunting deer, and feral hogs, is a much better choice for self defense use, and can put 120 gr. bullets out to 350 yds with no strain. Try talking to people who actually use it before badmouthing it.

    • 5.56mm the premier hog hunting round in my experience; 6.8mm is rarely used.

      • Mad_Gorilla

        You really ought to spend some time on 68forum, and talk to the guys who run hunting ranches down in Texas, among other places. They’ll set you straight on what works on feral hogs, complete with video of hunts.

        • I have been lurking on 68forums for years. 🙂

          I would imagine that most folks on that website would hunt hogs with a 6.8mm.

          • Mad_Gorilla

            Yeah, and they also use other cartridges. They use 6.8 the most because it has proven to be the best for hogs out of an AR. If you’re lurking over there, you should know what is fact and what isn’t. You should know who Harrison is from ARP. There’s nobody who knows more about these calibers in the AR platform than him. He’s one of the guys who corrected the mess Remington left in it wake when they walked away from the 6.8.

          • I know what the 68forum thinks is fact. 🙂

            And I know nobody over at AR Performance would like my ballistic charts very much. 🙁

          • Core

            Blah blah.. You are making an issue out of nothing, and don’t go claiming the 6.8 is a better man stopper because it isn’t. By and large the 6.8 was a failed attempt to create a superior cartridge to replace the 5.56 nato.

      • toms

        5.56 is definitely not a premier hog hunting round. It works adequately with TSX bullets but its not great by any means. People use it because its available cheap and tactical. I have shot hundreds of hogs with both types of calibers. 6.8 is way better. 5.56 is not consistent or predictable in how it behaves in flesh. As a former invasive species biologist I say your really out there on this one. Call some of the big hog ranches in Texas. They do more post mortems on dead pigs and know how different bullets behave in flesh than anyone. Many of them live this discussion. 6.8 is not perfect at all but it delivers quite well in the pig killing arena and by default in the human killing arena as well. 0-350 yards no contest at all. In fact 5.56 rounds kill pigs better at high velocity (lower weight like 55-62 gr max) from what I’ve seen. The 70grs just kind of punch through.

        • By “premier”, I meant “far and away most popular”.

          How is the 6.8 less “tactical” than 5.56?

          I have never claimed the 6.8mm wasn’t adequate against hogs. Actually, I think hog hunting is one area where it really shines, at least in terms of performance. It’s got good factory loads, plenty of energy at short ranges, and fits in an AR-15 with minor modifications.

          In fact, I even say that in the article.

    • Alex Nicolin

      As I said in a previous discussion, both are marginal at best due to the low SD. 100 lbs would be the maximum size of the quarry.

    • Core

      Unless your target is at 600 meters. Or armored at 300 meters. Just sayin.

    • iksnilol

      So can 7.62×39 (300 meters = no problem for average AK) yet noone is touting it as a miracle cartridge.

  • Dark, the 6.8mm SPC was designed for the Mk. 12 SPR (hence the “special purpose” in the name), and if that’s not an accurized designated marksman’s rifle, I do not know what is.

    I compared the two rounds out to 1,000m to give a thorough comparison. Both are designed for medium range (300-500m).

    • Darkpr0

      If that’s the case, then attacking the problem by moving up to 6.8 calibre would seem to be going the wrong direction. Knowing that the cartridge length is limited by the infrastructure of the current weapon system in 5.56 they had to know that the end result was going to be a less slender bullet. That being the case, they must be banking on superior terminal effects because they’re not going to get better energy retention over range.

      That said, I don’t see a ton of wounding power either. It’s competing against lengthened 5.56 and 6.5 Grendel which are both long projectiles with a lot of yawing power. Grendel in particular has a lot of energy retention to enable particularly violent yawing if the bullet design is optimized for it. I’m just not sure what would convince Remington that they could outdo those competing rounds by going this direction unless they’re going for a completely different wounding method. It won’t fragment and if you want particularly nasty pencil holes… Well I hear good things about 7.62x39mm on that front. 9x39mm would be an adventure for that as well.

      It would be nice if someone could test the rounds against ballistics pigs at the appropriate ranges. But neither the pigs nor rounds would come cheap, unfortunately.

      • You nailed it. 🙂

      • Guest

        Nailed it!

      • hikerguy

        You should come to Arkansas. We are overrun with feral pigs. The farmers would love for all of you to come and test rounds to your heart’s content, LOL. You don’t even need a permit….(well, except for a basic hunting license).

        • BaconLovingInfidel

          That’s the entire Southern half of the US now, I think. Free pigs for all. Just watch out for the tusks.

  • Alex Nicolin

    Very good analysis indeed. I’ve read it with the ballistics calculators and a certain spreadsheet opened. As I side node I would add that the 6.5 Grendel would offer a much better compromise in terms of ballistics from an AR15 platform due to the better BC and SD.

  • Blake

    Great analysis. & judging from the # of comments it’s obviously stirred up some reactions.

    Personally I’ve thought for some time that if .mil wanted the most oompf for the least cartridge weight (one of the manifestos of the 5.56N caliber) then the way to go would have been a weapon system that could crank out a high-bc 20 caliber bullet (think 75ish gr.) at 3200+fps from a 16″ carbine bbl.

    This would provide sniper-caliber-grade ballistics for the average infantryman, with enough energy left after the trip to get the job done.

    But of course there are far too many barriers in .mil for something like this to actually happen…

    • A 75gr .20 cal bullet would have to be made of uranium to be spin-stabilizable.

  • Brian

    Just a novice, but couldn’t we just go back to the 308?

    • iksnilol

      Already thousands if not millions of 5.56 rifles in service. Would be expensive to replace them + cartridge weight and the fact that your average soldier isn’t going to take advantage of the extra range. Those are my guesses.

      • hikerguy

        There was a study done after WW2 that said no more than four out of every 100 riflemen was effective. They primarily used the .308 (.30-06) in that day. More info to back the point you made. 7.62 for designated marksmen and 5.56 for everyone else.
        I do find it interesting the British army in Afghanistan started equipping their troops in desert areas with AMTs version of the AR10 because the Taliban’s .303 Enfield copies outdistanced the Brit’s 5.56 bullpups. Another example for DM and the 7.62.

        • L Mario

          Hiker, very good point. Also, notice how it’s been days and notice how gNat is nowhere to be seen.

          • It’s been days and you 68forums guys still are so ruffled you gotta come in here and insult me.

  • ghost

    If only, military wise, we had a 30-06 or a 7.62/.308, and women strong enough to carry them. Dead horse, quit beating.

  • ebd10

    I’m nowhere near an expert but, it seems to me, that the progenitors of this cartridge went around the block to get next door. There had already been a lot of work done on alternative cartridges in the M4 platform. Instead, they started with an obsolete, out-of-production cartridge and came up with something that is marginally better than the 7.62X39.

    The 6.5 Grendel may not ne the right choice, but it seems that it would have been a superior starting place.

  • Core

    I don’t think it’s logical to think the SPC could ever be a DMR cartridge (mentioned by Nathan), yet I can see the appeal as a way to punch a larger hole for close combat. I ran these ballistics a while back and realized at 300 meters the SPC falls short. I also checked the Blackout and Socom cartridges and none of them show a overal benefit over the 5.56 Nato. The shape of the SPC projectile is more suited for subsonic flight, versus a conical shape suited for supersonic flight. There must be an assumption that the projectiles will at some point travel subsonic and still be required to maintain accurate flight. There may also be a stabilization issue with conical projectiles, but I would think that the 5.56 at 3000 fps should have a conical tipped projectile , it would seem that the energy and supersonic performance would be substantially better. This would also allow more mass behind the projectile in a shorter distance with greater supersonic performance.

    • *shrugs* That’s what it was designed for. I agree it’s a bit baffling.

  • Core

    I just converted the flight speed of the 5.56 Nato @ 3000 fps to 2045 mph and 1000 fps to 681mph. 1,127fps is supersonic. The cartridge is not lethal at the range at which the projectile drops below supersonic. So switching to a conical tipped projectile would enhance ballistics and cause rapid reduction in velocity beyond 950 meters.

    • How is a 62gr bullet moving at 1100 ft/s “not lethal?” That’s comparable performance to .32 ACP.

      • marathag

        22LR can be less than that, and still kill with 36gr

      • Core

        Aim at a man sized target at 950 meters with your M4 and let me know if you kill it? That’s what I mean sorry for the confusion: effective lethal range. I’m off on a tangent because I just realized I could design the projectile to be much more effective in 5.56 Nato. It involves some principles I’ve learned from my experience in aeronautical engineering. Great article, and Happy Easter!

        • Thank you for the kind words.

          I am not arguing that the 5.56mm is a good performer at this range, I am just wondering that you keep using the word “lethal”. Do you mean that the 5.56mm has low lethality – i.e., that it does not stop or kill a human target quickly? I would say that is likely. However, it is still quite “lethal” in the normal sense of the term, i.e., that it can kill.

          • Core

            I’m referring to the ability to neutralize a threat in the combat zone, down range. I’m not saying it doesn’t kill a Human target quickly, it does in fact kill very effectively. We get stuck on various tangents when discussing which cartridge is better but we have to remember the effectiveness is the end outcome the effective application of the cartridge. I set out years ago trying to find a better cartridge to build a better Stoner rifle, and I discovered the 5.56 nato is the total package to date. To develop a better cartridge will require all source analysis of the battlefield and expansive use of technologies both in the weapon platform and the cartridge components. We are currently on the fringe of such a discovery, but making it happen happen, delivering i to the battlefield is another issue in itself. I believe a .25 will be a good place to start, and possibly caseless.

  • MarylandShooter

    To write on a topic, you should have basic subject matter understanding. While I see pretty charts and graphs, the article is lacking facts.

    Money talks and bullshit runs the marathon, so let me cut to the chase and say I’ll put up what the writer would like to wager.

    He’s using way outdated data in drawing incorrect conclusions and the really sad part is someone gave him space to promote absolutely false nonsense. Shameful and shooters are some of the worst sources of information available.

    I’m calling on the Firearm Blog for an opportunity to rebut this garbage piece and after that, a complete retraction from this self-described “small arms know-it-all” who is an unmitigated embarrassment.

    • Which facts do you feel my ballistic analysis lacks? By what newer data were the data I used obsolesced?

      • MarylandShooter

        I think the only thing you got right was your name. Why don’t you buy a 6.8, get a chrono and go get some real life data. After that, move on to reloading and really feel the benefits of the 6.8 because this data has to be 10+ years old my friend.

        If TFB wants to pay me, I’d be happy to demolish your “article” with an accurate review of the 6.8. With all due respect, you have no idea what you’re talking about. I’m sorry to have to be so blunt, but there’s no nice way to say it really.

        You up for a wager? I’ll go $1,000 donated to the charity of the winner’s choice. All we need is a impartial judge. It’ll be fun, educational, shooters get the facts and a charity gets a donation. Everyone wins.

        • Do you feel this is not real-life data? Keep in mind, the bit I’m using for reference is this:

          That’s Silver State Armory ammunition (which runs pretty hot) through an AR Performance barrel (that’s a barrel made by a gentleman who posts as “constructor” on 68forums), running right up against the 55,000 PSI MAP of the 6.8mm. No one who feels the figures I used were too low has yet explained to me why this combination was not satisfactory.

          You contend there are serious problems with my article, but that my website must pay you to know what they are, is that right? Frankly, that’s absurd. I know of no website that would accept that deal. On top of that, you want me to throw down a cool grand for a bet on what? Exactly what are we betting on, again?

          • MountainKelly

            Fanboyism is a strange mistress

          • MarylandShooter

            I’m saying you were paid to write an article that is patently incorrect. I’ll be happy to write an article that is correct and I’ll expect to be compensated for my time just as you have been.

            I know Constructor and some others at 68Forums. They are all having a good laugh at your attempt to write an article about the 6.8 SPC. It’s failed in epic fashion.

          • If his article is so terrible, surely it should be easy for you to post data which rebuts it?

          • You are a reprobate. Before I began writing here for a paycheck, I wrote tens of articles – many of them for free – over at my personal blog. Before that, I wrote hundreds of articles over at another blog and didn’t see a cent beyond the nominal ad check.

            I proved that my writing was worth getting paid for by writing consistently and at length for years before I got this job. What have you proven? That you talk big?

            Put up, or be quiet.

          • PS, mate, I saw yesterday your forum’s site went down from all the excitement.

            Have fun hating on me.

          • Tassiebush

            You’ve made the effort to post these comments but you haven’t presented an argument. Why does presenting an argument require payment? Surely if Nathaniel has got so much wrong as you claim then it’d be easy to argue at least one point!

          • Tass, MarylandShooter has done this before; he wants a blogging job without having to work to get one.

          • Tassiebush

            It sure does look that way! You’ve done a remarkable job of answering so many comments BTW! Respect!

          • It’s been fun, really. I like talking to people.

        • tts

          Stop with the internet tough guy trash talk and present some evidence that backs up your disagreement with the article.

          Should be easy to do since you know what you’re talking about right?

  • Kris Costya

    even for TFB this thread is a circle jerk of epic proportions

    • I think “flame war” is the term you’re looking for. 😉

  • Kivaari

    This is a very informative article. I had considered buying a new upper to give it a try – knowing, “It just had to be better than a 5.56mm” – or so I thought. Thanks for your effort on this article.

    • Kivaari, thank you for your kind words. Please do not let this article stop you from buying a 6.8mm upper if you want to. In my opinion, the more the merrier. I don’t hate the 6.8mm cartridge, though some here clearly think I do because I am willing to analyze its ballistics. It is a fine cartridge, especially for hunting.

      However, if you were looking for a “DMR” type rifle with good ballistics to 500m, I would recommend a rifle with an 18″ Centurion Arms barrel in 5.56mm, instead of a 6.8mm upper. Ammunition suitable for use in that upper is much more readily available, and the ballistics are at least as good.


      • iksnilol

        What’s the ballistic difference between a 40 and 45 cm barrel in 5.56? For a DMR build wouldn’t a 50 cm barrel be best?

        ARs aren’t really my forte so I am curious.

        • It depends on the exact load, but Mk. 262 was designed for the 18″ Centurion Arms barrel.

          • iksnilol

            Ah, makes sense. I just like flexibility/simplicity so I bare around more common ammo like M855.

  • UnrepentantLib

    Seems to me this whole business is an exercise in false economy. Like when the British decided to go with a rimmed .303 cartridge for the Enfield so they could also use it in rebarreled Martinis. Whatever they saved in the short run they lost in the long term in the hassles of using a rimmed cartridge. If the 5.56mm won’t do it, then figure out what cartridge we need and build the gun around it. Trying design a cartridge within the constraints of an existing weapon guarantees you’re going to make too many compromises. Just my thought.

    • Georgiaboy61

      Re: “If the 5.56mm won’t do it, then figure out what cartridge we need and build the gun around it. Trying design a cartridge within the constraints of an existing weapon guarantees you’re going to make too many compromises.”

      You are absolutely correct that it is sometimes wise to start with a fresh, clean sheet of paper. The history of the M4 Sherman tank provides an example; in that case, it was trying to up-gun the Sherman to deal with the progressively better-armored German tanks and AFVs the Anglo-American allies were encountering after the invasion of Normandy.

      Although there were enough effective stop-gap solutions developed to see the tank through to the end of the war in Europe – such as the 76mm M1 family of guns, the British 17-pounder anti-tank gun, souped-up HVAP-tungsten cored ammo., etc. – the ultimately problem was the basic design of the M4 itself – among other things, the turret ring was too-small to allow a turret sufficient in size to accommodate a larger and more-effective main gun. That problem was solved with a new design – the M26 Pershing and its M3 90mm cannon. The M26 family was not without its teething troubles, either, but that’s another story…

      Being penny-wise but pound-foolish – believing in false economies – can definitely cause trouble. As a retired army NCO friend of mine says of the military procurement system, “Just remember – your weapon was built by the lowest bidder”…

      • Interestingly, it seems the M4 Sherman is pretty underrated these days. This post is a work in progress, but it covers a lot of the basics.

        • n0truscotsman

          the “tanksandafv” website has a couple articles that pretty much debunked a lot of the Sherman myths that are commonplace. The more I research the history, the more the Sherman gets vindicated with me.

          I have no problem saying it was the best overall tank of the War. The Centurion would have taken that title had it been introduced a year earlier.

          • The guy who runs that site is a good friend of mine. 🙂

        • Georgiaboy61

          Under-rated in some, over-rated in others…. the history of the M4 is nothing if not complex and interesting to boot. Steve Zaloga’s books on the Sherman for Osprey Military are very well-researched and notated.

        • Georgiaboy61

          Interesting blog, but far from authoritative – there’s nothing there that Steve Zaloga and others haven’t already done better.

          • I don’t think he meant for it to be authoritative.

        • Jay

          The M4 was an awesome tank, when was first sent to war in Africa. The German Panzer III and Short barell Panzer IV s were not that hot back then. Only when the Panzer III and PanzerIV swapped rolls , the 75mm AT gun used in the P4 gave it an edge in firepower to the Sherman.
          However, by the time the Sherman landed in France, the AT guns the Germans used on the western front, were significantly more potent. Some of the Shermans got a better gun, but the armor was still awfully inadequate for 1944-1945.
          No enough propaganda can compensate for the horrendous losses the Sherman units had in 1944-1945.

          • Don Ward

            The primary role of the tank in WW2 was still infantry support for which the Sherman’s numbers, mobility and 75mm gun excelled. Even at AT work, humble 75mm equipped Shermans were more than capable of holding their own at average combat distances.

      • Don Ward

        The M4 tanks stomped the vaunted Panzers including the overrated Tigers and Panthers throughout the war and saved the lives of countless GI and Tommy infantrymen before going on to serve in the Cold War. If anything, your anecdote proves the dangers of relying on conventional wisdom in favor of cold hard facts and data.

        • Georgiaboy61

          Don, I don’t deny that the Sherman was a war-winning weapon, but its inadequacies cost the lives of far-too-many brave allied tank crewmen.

          As far as cold hard facts and data, I’ll argue them with you anytime, anywhere. Bring it on.

          The Sherman was an adequate weapon, and then only barely so – made “successful” only by sheer numbers produced and the bravery, ingenuity and resourcefulness of the men who used the tanks.

          If you have not already done so, you might consider reading the late Belton Copper’s “Death Traps,” a memoir of his service as an ordnance officer in the 3rd Armored Division. It is probable that Cooper saw more destroyed and battle-damaged Shermans than any man in the ETO – in addition to being a trained engineer. He was very well-qualified to assess the design – not to mention the fact that he was in constant contact with the guys crewing the tanks, and thus knew their opinions of the design thoroughly, not only the good, but the bad and the ugly, too. Cooper’s assessment mirrors that of many other soldiers…

          Re: “The M4 tanks stomped the vaunted Panzers including the overrated Tigers and Panthers”

          I have been privileged to know a good number of WWII veterans personally, including some veterans of armored warfare in the ETO. Not many of those guys would say we “stomped” the Panzers; the tale they tell is that the Panzertruppen were very tough to defeat – and our tankers managed to do so only at great cost to themselves paid in blood, courage, lives – and destroyed tanks.

          The “real” miracle weapon was not the Sherman itself, but the vast system for the recovery, repair and refitting of battle-damaged tanks and AFVs. When the Germans lost a Panther or a Tiger (or another AFV) in the field, it was often lost for good – not only because of advancing allied forces in some instances, but because the Germans didn’t have anything comparable to our system for recovering and repairing damaged AVFs in the field under combat conditions.
          As for your accusation that I am guilty of “conventional wisdom”do get over yourself. Your opinions are just that – opinions.

          • Alright, then. Since you’re asking for facts, here’s some excerpts from US Army Ballistic Research Labs reports on the performance of the M4.

            Not looking too good for the Germans, is it?

          • Georgiaboy61

            The crucible of combat is the only test that matters…. and the army had (and still has) a long and well-proven record of fudging or outright falsifying test data for political and other reasons – or simply ignoring information which contradicts the received wisdom. In the case of the Sherman, that took the form of rear-echelon chair-warmers (many of whom lacked any combat experience in tanks whatsoever, let alone combat time in WWII) making poor/questionable design decisions for which good men paid the price in blood.

            The Sherman entered the war in North Africa, where it performed adequately, at times even very well, against German Pz.Kpfw. IVs and other older designs. Since the Tiger I was then fairly new and not being used yet in significant numbers, the threat it posed to the Sherman wasn’t fully-appreciated. Keen observers even then, however, were already noting the horrific toll being taken by dual purpose 88mm anti-tank/anti-aircraft guns. That should have served as a warning, but didn’t. Nor did the emergence of the new Mk. IV “Special” with its long-barreled high-velocity 75mm main gun – which also proved deadly to the Sherman’s thin armor.

            As we invaded Sicily and then Italy proper, we continued to take heavy losses against German tanks, TDs, SPs and fixed AT guns, but these were written off as a product of the mountainous terrain or blamed on the crews themselves. Protests from crews themselves, junior/mid-level officers and from the families of dead/wounded tankers were brushed aside.

            If we’d have been wise, we’d have profited from the experience of the British/CW armies and the Russians, both of whom had fought German’s best tankers for much longer than we had – and both of whom understood the essential armored warfare arms race then in effect – i.e., for larger and more-powerful guns with ammunition capable of defeating enemy armor, for thicker and better-sloped armor plating, and for better fire-control systems. The British offered us the 17-pounder anti-tank gun, then arguably the most-effective anti-tank weapon in their arsenal.

            We turned it down, since General Eisenhower was told that the new American 76mm cannon could defeat any German tank it encountered on the battlefield – a contention which was later proven to be a bald-faced lie. That’s why we invaded Normandy in June, 1944 with Shermans still largely armed with the short-barreled M3 75mm cannon – a weapon which was incapable of penetrating the frontal armor of a Tiger or Panther – even at point-blank range. The M3 was an effective general-purpose cannon and infantry-support weapon, which fired excellent HE and WP rounds, for example, but it was a bust as an AT weapon against the newest, best-armored German designs.

            To add insult to injury, the much-hyped new 76mm gun under-performed expectations considerably – so much so that Ike later complained that he’d been told it would be the wonder weapon of the war, when it was actually incapable of penetrating the Panthers and Tigers reliably at routine combat ranges. The 76mm gun eventually performed well-enough that it attained a degree of success against German armor, but that was mostly using tungsten-cored HVAP ammunition. Since tungsten was in chronically-shot supply to the end of the war, our tankers never had enough of these sought-after rounds.

            The 76mm gun had better anti-tank performance than the short-barreled 75mm, but its HE round contained a smaller charge than its predecessor and was therefore less-effective as an infantry-support round.

            The tank destroyers saved the bacon of a lot of Sherman crews, as the appearance of an M36 with a 90mm cannon could turn the tables on many variants of German armor. The same proved true with the Archer and Achilles, British TDs armed with the 17-lb. gun.
            The 17-pounder, firing armor-piercing capped ballistic capped (APCBC) ammunition, was capable (in theory) of penetrating up to 130m of armor at 500m and 119mm at 1000m at a 30-degree angle; firing armor-piercing discarding sabot rounds, the gun was capable of attained the then-stupendous muzzle velocity of nearly 4,000 fps. This was attained using a sub-caliber tungsten carbide core of 7.6 lbs. encased in sabots to bring it up to full caliber; once fired, the sabots fell away and the sub-caliber projectile – being much-lighter than the standard full-bore 17-pounder projectile – could attain very high velocity sufficient to defeat armor that had been heretofore, impregnable to Allied guns. APDS could defeat up to 204mm of armor sloped at 30 degrees @ 500m, and 185mm (same slope) @ 1000m – but in practice, the round proved to be less-accurate than the conventional APCBC load, and kills of enemy armor were seldom made at those ranges.
            Armed with the 17-pounder, the Sherman was a formidable weapon – if it managed to get in the first shot against its German opposite number. The potent gun did nothing to address the inadequacies of the Sherman’s armor, but at least the crews so armed had a better chance to come out of an engagement alive than previously. Of course, the Panzertruppen quickly learned to target the most-effective allied AFVs first – and then move on to the less-difficult 75mm Shermans. In any case, the U.S. didn’t have the 17-pounder, since the “geniuses” at Army Ordnance turned it down. A classic case of not-invented-here syndrome at work.
            In addition to its inadequate armor, main gun and ammunition which was originally poorly-adapted to fighting other tanks – the Sherman also suffered from other defects.
            During WWII, in the era before the electronic battlefield and all of its advanced sensors, lasers, targeting computers and the like, being able to sight the enemy and engage him before he did the same to you – was often the key to winning and surviving – or not. The Panzertruppen and Wehrmacht tanks benefitted from optics designed/manufactured by the world-renowned German optics industry. Other things being equal, their superior optics allowed German crews to see, range and engage targets sooner than their allied counterparts. The allies off-set this advantage by using aerial spotters flying ahead of armored columns – but matched one-to-one, their sights, optics and rangefinders were superior to ours – as they were superior to those of the Soviets.
            Despite being outweighed by larger and heavier German tanks such as the Panther and Tiger, the Sherman still had higher ground-bearing pressure per square inch, due to the fact that its track was narrower than that found on the newer German designs (as well as on the T34). The M4 was therefore prone to bog down in soft ground and in the mud. Later versions of the Sherman had improved tracks, but the problem was not solved entirely. This problem was exacerbated by the severity of rain and snowfall during the winter of 1944-1945 across N. Europe.
            Due to the nature of its transmission, the Sherman could not turn within its own length or nearly-so, as could the Tiger and Panther – whose transmission and track designs allowed this feature.
            The Sherman had a high silhouette – and was thus more-easily sighted on the battlefield, and was more-difficult to campflage.

          • John Conquest

            GeorgiaBoy, that was an excellent post and you have my utmost respect. I just wish that fewer fact deniers and revisionists were here. Kill ratios and interviews with tankers tell all that we need to know about the Sherman — it was adequate until it went up against something good. Coincidentally, it was also called the M4. Funny how that keeps happening.

          • John Conquest

            Good job, linking to a wargaming blog article with no numbers, just a lot of opinion and something based off of one obscure book that’s only for sale on amazon. Post by post, you look weaker and weaker.

          • It’s not a Wargaming blog article, and it’s not just based on that book. It’s substantially based on a US Army Ballistic Research Laboratory report, a reprint of which can be found on Amazon, as well.

          • Georgiaboy61

            Thanks for the compliment… however, there’s plenty of room for dissenting opinion, and military history buffs love – and I do mean l-o-v-e to argue…
            For me, it all boils down to what the crews themselves thought of their tanks. Don’t get me wrong, engineers, designers, ordnance specialists, technicians, metallurgists, etc. all have their vital place, but when it comes down to it, the guy who actually fought the tank – his is the opinion that most matters to me. He’s the guy whose neck has been on the line in battle, not the rear-area chair-warmer types.

          • Georgiaboy61

            Took me a while to get what you were saying about the M4…. DOD/Pentagon nomenclature never dies, but only fades away to be recycled at some future day. To be fair to the guys in the five-sided puzzle palace, they aren’t the only ones guilty of recycling hallowed names. Browning now calls a semi-auto hunting rifle the BAR; that model has been out for years now – but to an old-school guy like me, that’s sacrilege. Invent an original name for the darned thing, know what I mean?
            Well, you know what they say -what goes around, comes around.

          • n0truscotsman

            The problem with the Sherman is the quantity of anecdotes and unsubstantiated claims, not to mention improper comparisons between a_single_ variant of sherman to other tanks.

            I think you made several excellent points, georgiaboy, but a couple that I would like to address. Forgive me TFB for venturing off into tank lala land 😉

            1.) There is no doubt that comparing medium tank to medium tank, the Shermans were comparable to their peers. Likewise, against other allied tanks, the 88s were deadly. There was no getting around the 88 problem, other than just up armoring to insanely impractical levels (or inventing composite armor earlier, a non-starter).

            2.) Early US involvement in Europe demonstrated our inexperience compared to the highly experienced Germans. This was the unfortunate side of our entry in the war against the Axis. To blame the high losses in armor in Italy on the Sherman, I think, is way off the mark. What other US vehicle in production could have been more survivable against 88s and emplaced AT guns? Furthermore, Ill lay the blame on poor tactics and underestimating German determination in Italy’s “soft underbelly”, rather than the deficiencies in armor (more to follow on why it wasn’t a bad choice).

            3.) The British employed Shermans to a respectable degree, i.e. the Firefly, as did the Soviets. There are a number of sources that are interesting, most notably this

            Our Allies and adversaries recognized the Sherman for what it was: a easy to manufacture, inexpensive, robust, reliable, and easily modified battle tank.

            Ill also add that the US DID understand the armored arms race, which led to the employment of the 90mm gun and Pershing tank, which was a evolutionary progenitor to the excellent Patton line of tanks that still serve today. Time was limited to employ the heavier armor and guns into the european theatre since we were racing the Soviets to Germany (a race that Patton and Churchill understood ill add). But that is a whole other issue of debate.

            4.) Speaking of the Firefly and the 17 pdr, i believe it was criminally abysmal to not adopt it, since it COULD face Panther and Tigers. The 17 pdr, not without its own problems, was an excellent anti-tank weapon. You highlighted all of the reasons excellently.

            I also agree that the 75mm was an excellent infantry support gun that left much to be desired against armor, although, per army doctrine at the time, that job was suited for the hellcats and other TDs. The 76mm was another compromise in its own way.

            5.) Where I disagree with you is the criticism of the Sherman’s armor. While there is little doubt that it lacked the protection of the Panther or Tiger, for example, but comparing it to other medium tanks?

            Even the heavy armor of the Stalin tanks fared very poorly against the 88mm AT guns. There was no solution at the time to the 88 other than adding significant amounts of armor to the tank, increasing its weight to 50-60 tons (modern MBT weights, without the mobility and modern power plants to achieve a favorable ton per hp ratio).

            6.) On the ground PSI figures, I believe you are half right with your contention, and it is covered in the website I cited above. Scrolling down to points 7 and 8

            Note: there is much contention over the book “Deathtraps”, which is also highlighted in the link. It is worth the read.

            But to make an adequate comparison, you have to compare ALL versions of the Sherman (which ARE different) to versions of the panther and tiger.

            M4A1: 13 PSI
            M4A2: 14 PSI
            M4A3: 13 PSI

            Other variants with the 76mm venture within the 14-15 psi range.

            However, when the HVSS was introduced, this figure was reduced to 11 PSI. Significant improvement.

            Now venturing to the Panther, which as 12 PSI, the Tiger I, 13 PSI, and the Tiger II, 14 PSI.

            So the answer to “do german panther and tiger tanks have a lower PSI than Shermans?” is “yes and no, depending on what you’re comparing it to”. Keep in mind that HVSS wasn’t introduced until later in 1944 and the A3 seemed to the the preferred variant used by US forces.

            7.) “This problem was exacerbated by the severity of rain and snowfall during the winter of 1944-1945 across N. Europe.”

            The rain and snowfall, and mud (especially on the eastern front), also profoundly affected both the Panther and Tiger, due to the previously mentioned interweaved road wheels and complex track system.

            “The Sherman had a high silhouette – and was thus more-easily sighted on the battlefield, and was more-difficult to camouflage.”

            The Sherman was 9 ft tall, the Panther 9ft, 10 inches, the Tiger I, 9ft, 10 inches, and the Tiger II, 10ft, 2 inches. So the Sherman had an edge in terms of silohette, although consider that the T34 had a height of 8 ft, the cromwell, 8 ft, 2 inches. The Panzer IV had an edge of 8 ft, 10 inches, giving it a slight edge of two inches over the sherman.

            So in comparison to other tanks, the Sherman silohette wasn’t a problem.

            8.) In terms of the fire hazard, you are absolutely correct. Ammunition fires were a problem and the Sherman’s survivability increased substantially with the introduction of the wet rack. This highlighted the inherent importance, however, of diesel power plants of tanks. Hard lessons paid for in blood.

            9.) Pertaining to the power plant, radial engines were only used in the M4 and A1 variants, with the ford V8 used in the A3, a multibank engine used in the A4, and diesel radial used in the A6.

            I agree that aircraft engines have many disdvantages when used in tanks, and this is still true to this day in the diesel vs gas turbine argument in modern battle tanks.

            Their advantages in light weight, ease of replacement, and constant power are off set by their high maintenance, high cost, and delicate attributes in combat conditions.

            10.) On your last point, I disagree and will say that the Sherman’s most notable features, namely its low cost, ease of manufacture, and mechanical simplicity, not to mention its flexibility in hindsight, contributed greatly to the Allied war effort. It evolved into one of the finest tanks ever fielded by an armed force, as demonstrated later in Korea.



            There is more to the effectiveness and viability of tanks than just slugfests with enemy heavy tanks.

            again, i apologize. Way off subject, but i couldn’t resist. 😉

          • Georgiaboy61

            I wrote a lengthy reply to your comments, but even though I posted it last night, I don’t see it anywhere. I don’t agree with all of your points, but I do with some of them. Let’s leave it at that. Probably for the best anyway; this thread isn’t supposed to be about the tanks of WWII, as fascinating as they can be. Cheers…

          • n0truscotsman

            likewise 😉

          • Don Ward

            If you want to gain the respect of others, not parroting debunked history channel myths about the Sherman tank is a place to start.

          • Hey guys, I think you two can get along. 🙂

          • Are you saying that my autographed copy of “Death Traps” is wrong?!
            I need to sit down and reevaluate my life choices.

          • n0truscotsman

            As i cited above, there are many problems with using “Death Traps” as a source when comparing armored vehicles used during WW2, particularly, when having a discussion about the Sherman.

          • Georgiaboy61

            Re: “If you want to gain the respect of others, not parroting debunked history channel myths about the Sherman tank is a place to start.”
            Respect from the likes of you I do not seek; indeed, your disapproval I wear as a badge of honor.

          • Don Ward

            Look, if you want to trump up and swoon over Nazi Panzers while belittling the efforts of the men who designed and fought in the M4 Sherman while ignoring the simple fact that the Sherman ran circles around German tank design and outfought them at Arracourt and the Battle of the Bulge then that’s on you.

            But please change your user name to GermanFanBoy41 if you insist on doing so.

  • Dan

    So much 6.8 butthurt. It pleases me.

  • TDog

    But, but… the round is “Special”! As in Special Forces! The only way it could be more lethal and more deadly and more warrior-like is if they added the word “black”, “commando”, “recon”, “stealth”, and/or “delta.” Then it would be able to kill eighteen men in one hit from a range of ten miles!

    Seriously though, I never saw the point of it. .308 kills people just fine at ranges greater than the aforementioned rounds in the summary. So unless terrorists, communists, and anarchists have suddenly grown immune to any round that starts with a “.3” or “7”, I think .308/7.62×51 will do just fine.

    • iksnilol

      Hard to fit 308/7.62 NATO in a 5.56 magazine 😉

  • Which is fine (though it’s technically not “going out of business”). I am not sure how it indicates that the figures I am using are too low (as Gorilla argues), however.

  • The data I am using is literally referenced from SSA ammunition fired from an ARP barrel. Why do I keep having to repeat this?

  • MountainKelly

    Well the fanboyism is great here. Decent read though

  • Georgiaboy61

    Fascinating article, Nathaniel – and very well-researched.

    Your regular readers know of your support for the 5.56×45 and the AR family of weapons. We get that. However, what would you choose if neither was available and you were charged with arming the typical American soldier with his standard long arm?

    Continuing our thought experiment, if you were put in charge of small-arms procurement for the military, and given the budget and authority to make things happen, how would you arm them – if the 5.56 and AR family of weapons were off the table? Since you’ve got the budget and clout, consider that you are not limited to off-the-shelf technology – but can put out RFPs, conduct R&D, etc.

    • This is a great question Georgiaboy, and frankly I’m going to recommend folks upvote it so it can float to the top. I know you and I have gone at it before, but I’m more than happy to get into this.

      First, I’ll say that – obviously – I am not in charge of procurement in any way and therefore I am reticent to officially recommend a change. Fundamentally, I think the 5.56mm is fine until the next thing comes along, and I wouldn’t throw my weight behind any conventional proposal.

      However, I am fine with scuttlebutt on what might be interesting, so here goes.

      5.56mm is limited by its ogive length. This means it tops out at about a 1.09 i7 FF, which is higher than I’d like (lower is better for form factors). I think the first thing a next generation round should do is improve the ogive length of the bullet. I think the M855A1 bullet design is excellent, and so the bullet design ends up looking like a cross between the contour of 5.45×39 7N6 and the construction of M855A1.

      Obviously, you could come up with something more ambitious than this (sabots, flechettes, what-have-you), but I’m deliberately being conservative since I think that’s in the spirit of your question.

      So that’s the most important thing, a bullet with a lower form factor and a bullet design in line with the M855A1.

      Now we can get into performance. In my opinion, the fragmentation effects of 5.56mm rounds should not be given up. In fact, they should be maximized for both consistency and range. This means a high muzzle velocity and a high ballistic coefficient. Further, the recoil characteristics of SCHV rounds in my opinion provide a significant advantage, so I would try to avoid creating a round with as little recoil as possible. Finally, I would of course try to keep cartridge weight to a minimum, which means paying careful attention to the bullet weight as that incurs major penalties on overall cartridge weight.

      Fortunately, taking M855A1 and streamlining it along the lines of 7N6 gives you a ballistic coefficient of .190 or better (so along the lines of current Mk. 262 77gr ammunition, or better). So we might just be able to stick with the 62gr bullet weight. This will pay dividends later. Using the A1 EPR bullet design ensures yaw independence. And of course, it’s lead-free, appeasing the greenies.

      Velocity should be as high as is practical. If the fragmentation range is to be extended, you need a higher muzzle velocity. My experiments indicate that 3,000 ft/s is a very good place to be. I feel the peak pressure of M855A1 is also good.

      What does a .190+ G7 BC lead-free 62gr bullet at 3,000 ft/s look like, ballistically? It looks like Mk. 262 with a much flatter trajectory and higher velocities at a given range.

      If this were to be implemented with a conventional brass case (which I don’t recommend), it would require similar case capacity to 5.56mm, and if it were implemented in retrofitted AR-15s, a fatter, squatter case would be required, most likely based on the 6.8mm SPC case. Hahah.

      So in effect, I would give every rifleman something like Mk. 262 but with higher velocity at any given range, and a much longer fragmentation range.

      I may just elaborate on this in a proper post.


      • Nicks87

        What about the recoil from your theoretical cartridge? A big advantage of .223/5.56 is that it is fairly light recoiling which is great for follow up shots. With higher velocity comes more recoil. A ballistically superior cartridge may not be better from a combat perspective because now you need to slow down your rate of fire to deliver more accurate hits on target. Your round may perform better than .223/5.56 but if it recoils like a .308 then what’s the point. Just a thought and great article BTW.

        • It would have recoil very similar to 5.56mm, as bullet weight, velocity, and charge would all be very similar. A finer ballistic shape imparts no recoil penalty.

      • Brandon

        Looking at the graphs you MADE after all these years I have never seen a blue line just flatten out. Look at the Sierra BTHP energy graph. You see how the blue comes down in a nice sweeping curve and then when it crosses the red line it seems to flatten out? Is that a poor photoshop job or what? It dips below the red line then gets a burst of energy and jumps above the red line …odd.

        • Brandon, that is the transition from transonic to subsonic flight. Many ballistic programs do not account for it, which is one of the big reasons I use JBM’s calculator.

      • I don’t think “greenies” will ever be happy about bullets, no matter what they are made of.

      • Andrew

        Nathaniel, I feel 3000 fps from a 62gr projectile is acheivable from the ‘SPC’ case necked to .224. About 2months ago, I measured 13 shots m855 from a Noveske 14.5 in barrel. 500ft elevation, 55F, 51%RH, 30.40 pressure. Chrono was at 15 ft (measured). I got an average of 2933.3fps with an ES of 73fps.
        A few years ago I got an average of around 2950 from 10 shots(can’t find the logbook) in an M4A1 on a ~90F day on Benning at the same distance.

        • I believe so, yes. Of course, I would not worry too much amount conventional ammunition configurations.

          • Andrew

            Yeah, convential 556 ammo gives better terminal results than people give it credit for.

          • Andrew

            Good point. I find 7.62×39 to be inferior to most other mil rifle rounds. People will hate me for saying this.

          • Kivaari

            Some might, but considering the truth, you are correct.

          • Coolhand77

            just a suggestion…6.5 Grendel with an M855A1 style constructed bullet. High BC, adequate case capacity, yes, higher bolt thrust at higher pressures, but manageable, proven external ballistics [better energy/velocity retention]. Its got the external ballistics and energy, now it just needs a properly constructed bullet to meet military critera [maybe an OTM?]

          • Kivaari

            One of the known rifle makers has introduced a newer bolt style more suited to the 7.62x39mm, 6.5 Grendel etc. They use a .308 bolt with smaller face. It should be stronger than any opened up 5.56 bolt and probably stronger than the original .308 bolt. It makes more sense then taking so much materiel away from the lugs. It seems to be the most sensible approach.

          • That’s the obvious solution. There are some more elegant ones, however.

          • Kivaari

            I think it is CMMG. I don’t have my books handy.

          • It would perform similarly to the GPC I outline in “The General Purpose Cartridge Revisited”, but with lower velocity (probably about 820 m/s/2,690 ft/s from a 20″ barrel). So basically, lop the first 50 meters off that chart.

          • With a 6.5 or 7g bullet, you could get decent performance, I think, sure.

          • Kivaari

            Everyone should read the referenced document. The article explains in a better fashion what I’ve been saying. The AK47 simply doesn’t do all that much in tissue.

          • Kivaari

            That’s an excellent source. I had known that from other studies by his crew. This one I had not seen before. Now if all those that claim the bigger bullet from an AK is SOOO superior to 5,56mm would read it, they may see the light. The more I research and remember my earlier studies, the more I think we have one very good cartridge in a real good weapon. I was where I needed to be to find out about the pile of 6.8 ammo a friend has, and totally forgot to ask him. I am still thinking of getting a 6.8 upper, adding it to the HBAR set up I already have.

        • Andrew

          Also worth noting, adding a KAC suppressor (leave me alone ATF; military rifle, military can, military range, active duty shooter) was worth around 45 fps on that M4A1 at around the same time, place, and weather.

        • Blake

          Some wildcatters have been experimenting with 6.8SPC cases necked down to 20 caliber with very promising results: e.g.

          • Kivaari

            Small bore diameters, like 5.5mm has problems with water and burst barrels. Going smaller makes the problem even bigger. Water in the bore was an issue in Vietnam. One contributing factor was the 3-pronged flash hider, that funneled rain water into the bore. The A1 and A2 styles improved that by a small margin. More muzzle caps is a good idea. I found that using a 7.62mm bore allowed quicker water evacuation by “cracking the bolt” (pulling it back 1/2 inch) and I could see the water drain. The 5.5mm bores retained more of the water. A couple of opening and closing the bolt helped. The pumping action helped. You can demonstrate this to yourself, if you are not afraid of getting your rifle really wet.

      • noob

        What would you think of a DMR M16 derivative chambered in .223 WSSM that puts a M855A1 projectile downrange at more than 4000fps?

        I’m not sure that the projectile won’t break up immediately after leaving the barrel, but if it held together would you get greater than 3000 fps at 450m?

        The fatness of the WSSM case would reduce ammunition capacity so the non-DMR rifles would either need to use a different general purpose caliber or they’d need some kind of strange magazine to approach 20 rounds.

        • The case is way too short and fat for feeding in automatic weapons. I also don’t think you’d meet the velocity level in military length barrels.

          • Kivaari

            Olympic Arms has made some in the whole raft of WSSM calibers. I don’t know if they actually worked. I just remember a local store selling them a bunch of factory ammo.

        • Kivaari

          If we are getting a new rifle, how about a 6.5mm or 6mm in a 50mm case? We don’t need a new cartridge. Pretty much anything that needs a new rifle would be a waste. How much more can any 5.5mm – 7.62mm round deliver in a weapon the size of the M4 Carbine or M16 Mk12 that really makes it worth doing? The 5.56mm NATO is doing the job world wide as we talk about wasting money on something newer and maybe marginally better. Is getting another 50m out of a combination worth doing? Or would it make more sense to add more marksmanship training for every warrior. When I was in the Navy 67-70 we spent about an hour on rifle shooting. We used Remington M513 .22Lr at 25m. We were issued M1 rifles and M1911A1 pistols, with no additional training. I had an edge since I owned both weapons prior to going to Vietnam. I shot much more while in the Army. My kid learned on an M4 and M249. He was in Iraq and his weapon was the M249, which he never fired in combat or for qualifications. We need our warriors to be riflemen, trained more like a Marine. I fired more ammo while in high school and college than I did in basic training.
          Training makes a warrior with a M4 or Mk12 effective with existing arms. WE still don’t need new rifles or cartridges, we just need to train.

      • valorius

        you know, i agree with almost all your points, and would point out that we could just reissue M16A4’s and get the muzzle velocities you seek with the existing M855A1 round.

    • RAYAKE

      AR’s off the choice would be the M14 7.62/308,,cant go wrong and already in stock…

      • Kivaari

        The M14 had serious issues. It is one reason they were pulled from service. In the last 13 years a great deal of work has gone into improving the M14, A big problem early on were the stocks. Warping, catching fire and accuracy problems. New composite and metal stocks have helped. You can’t get around the over sized rifle. The M4 carbine is popular partially because of length and weight. A combat ammo load of 7.62mm is heavy and bulky. At the end of the day the soldiers load remains unchanged. A 5.56mm user has twice the amount of ammo having the same weight and bulk. An individual soldier might like his rifle, but while working in teams fighting a modern war, the M4 carbine makes more sense.

        • Georgiaboy61

          Some analysts, Barrett Tillman to name one, have suggested splitting the difference by arming a set number of riflemen in a squad or fire team with weapons chambered in 7.62 NATO, while keeping the majority of soldiers (or Marines, etc.) armed with weapons chambered in 5.56. You’d have 2-3 guys serving as DMs for a small unit, but the remainder would be carbine-armed. You’d keep the SAW in 5.56 or have the option of having a crew-served automatic weapon in 7.62 if tactical needs dictate. Seems sensible enough to me. Flexibility and adaptability is the key, IMHO. Let the troops have some latitude in choosing which gear best suits their mission profile; that what the special ops guys do – and if it is good-enough for them, it is good-enough for the average grunt, etc. What a concept – actually trusting troops to know best how to do their jobs!!

          • LilWolfy

            That’s been happening in many units for decades now. The mix of M110 and M4 pretty much covers this area well, but the M110 is getting scaled down in terms of barrel length and collapsible stocks so that it’s becoming a DM carbine.

          • Georgiaboy61

            Gotcha – thanks for the update.

          • That is essentially what we have now, I believe.

      • LilWolfy

        M14 was a failure from inception. It’s a rifleman’s rifle in how it feels if you love steel and wood, but as a military rifle, is was ill-conceived, ill-executed, and not supported well at all.

        It’s a very difficult rifle to maintain at an organizational level, let alone individual level. It doesn’t hold zero well, and malfunctions more than most will admit. It has a finicky gas system that requires a lot of tender love and care, and is an awkwardly long gun for many soldiers even in a green role outside of built up areas.

        There’s a special place for it in my memories, but I can set aside my personal anecdotes and see the forest through the trees: the M14 is dead as a service rifle, and should have never been pursued in the 1950’s.

        • This is very accurate, I find. The M14 has some redeeming features and handles very well, but it is decidedly primitive as a military arm by the 1960s

          It’s interesting that both US and Soviet small arms developments post-war ended up being Garand derivatives, but where the Soviets incorporated meaningful improvements to the design, the US designers were essentially constrained to the existing architecture (until 1953, the line of development leading to the M14 was literally confined to modifying old T20 rifle receivers – those being second-generation fully-automatic box-mag-fed Garands). Because of this, major architectural improvements such as the Kalashnikov makes over the parent Garand were impossible for the Americans.

    • David W

      “Your regular readers know of your support for the 5.56×45 and the AR family of weapons. We get that. However, what would you choose if neither was available and you were charged with arming the typical American soldier with his standard long arm?”

      I love how Nat’s response is to dance around the issue before saying something to the effect of wanting either an AR15 or a TOTALLYNOT!ar15 and something that TOTALLYISN’T5.56. So essentially Nate is so narrow-minded and has such a raging hardon for 5.56AR that he would rather throw around noncomittal obfusicating words than answer a question about what alternatives he would consider for a standard infantry rifle.

      • Georgiaboy61

        Nathaniel has made his positions known – that’s for sure. He didn’t actually answer the question quite in the manner intended, but that’s OK. I think I know where he stands.

        • If I didn’t answer your question as intended, I’ll be happy to make a second attempt.

          I admit, in the first read-through I missed that you were also asking me for suggestions on what a next-generation rifle might look like.

          • Georgiaboy61

            No worries. Go ahead and think/write about it some more, if you like. I’m sure many of us would be interested in what you come up with.

          • What was the manner intended for me to answer the question?

          • Georgiaboy61

            I was mostly interested in what you’d gravitate toward if the 5.56x45NATO and the now-serving AR family of infantry weapons were off-the-table. I think you did a pretty decent job of answering that already. IT would be interesting and enjoyable, however, to read your thoughts on the next-generation infantry long arm. I don’t see “Big Green” (the army establishment) adopting a new std. long arm soon, but then again, I have been wrong before. Some of what happens could be interwoven with the fate of Colt Arms – which now seems uncertain.

          • I think a few people were upset that I didn’t choose a caliber other than .22. Maybe I should have come up with a .20 cal cartridge… 😉

            Georgia, I think I am going to properly answer your question with an upcoming post.


          • Georgiaboy61

            Maybe you ought to up the ante by forcing yourself to choose three competing designs, each in a different caliber and each offering a differing design philosophy. Sort of like you’d see during the normal course of the government procurement process.

          • They would all be micro-calibers. >:D

          • Georgiaboy61

            Cool… so let’s hear about them.

      • Which words did you feel were especially obfuscating?

        • David W

          It looked like a question asking you to name some sort of weapon and cartridge, or at least a platform and caliber. Instead, you posted

          “This is a great question Georgiaboy, and frankly I’m going to recommend folks upvote it so it can float to the top. I know you and I have gone at it before, but I’m more than happy to get into this.

          First, I’ll say that – obviously – I am not in charge of procurement in any way and therefore I am reticent to officially recommend a change. Fundamentally, I think the 5.56mm is fine until the next thing comes along, and I wouldn’t throw my weight behind any conventional proposal.

          However, I am fine with scuttlebutt on what might be interesting, so here goes.

          5.56mm is limited by its ogive length. This means it tops out at about a 1.09 i7 FF, which is higher than I’d like (lower is better for form factors). I think the first thing a next generation round should do is improve the ogive length of the bullet. I think the M855A1 bullet design is excellent, and so the bullet design ends up looking like a cross between the contour of 5.45×39 7N6 and the construction of M855A1.

          Obviously, you could come up with something more ambitious than this (sabots, flechettes, what-have-you), but I’m deliberately being conservative since I think that’s in the spirit of your question.

          So that’s the most important thing, a bullet with a lower form factor and a bullet design in line with the M855A1.

          Now we can get into performance. In my opinion, the fragmentation effects of 5.56mm rounds should not be given up. In fact, they should be maximized for both consistency and range. This means a high muzzle velocity and a high ballistic coefficient. Further, the recoil characteristics of SCHV rounds in my opinion provide a significant advantage, so I would try to create a round with as little recoil as possible. Finally, I would of course try to keep cartridge weight to a minimum, which means paying careful attention to the bullet weight as that incurs major penalties on overall cartridge weight.

          Fortunately, taking M855A1 and streamlining it along the lines of 7N6 gives you a ballistic coefficient of .190 or better (so along the lines of current Mk. 262 77gr ammunition, or better). So we might just be able to stick with the 62gr bullet weight. This will pay dividends later. Using the A1 EPR bullet design ensures yaw independence. And of course, it’s lead-free, appeasing the greenies.

          Velocity should be as high as is practical. If the fragmentation range is to be extended, you need a higher muzzle velocity. My experiments indicate that 3,000 ft/s is a very good place to be. I feel the peak pressure of M855A1 is also good.

          What does a .190+ G7 BC lead-free 62gr bullet at 3,000 ft/s look like, ballistically? It looks like Mk. 262 with a much flatter trajectory and higher velocities at a given range.

          If this were to be implemented with a conventional brass case (which I don’t recommend), it would require similar case capacity to 5.56mm, and if it were implemented in retrofitted AR-15s, a fatter, squatter case would be required, most likely based on the 6.8mm SPC case. Hahah.

          So in effect, I would give every rifleman something like Mk. 262 but with higher velocity at any given range, and a much longer fragmentation range.


          This isn’t really an answer about what you would want to see replace AR and 5.56. The implications of your talk about the round outright state that it’s pretty much a MK 262 (a 5.56 round) shaped a bit more like a 5.45×39 7N6. “What does a .190+ G7 BC lead-free 62gr bullet at 3,000 ft/s look like, ballistically? It looks like Mk. 262 with a much flatter trajectory and higher velocities at a given range.” And your words about the gun don’t help much, either. “if it were implemented in retrofitted AR-15s” Remember the crux of the question, that AR’s and 5.56 are off the table. So it looked a lot like you dancing around the issue and trying to look like you were offering an answer while actually describing what could very easily be taken to be a weirdly shaped 5.56 in what you suggest could very well be a slightly tweaked AR.

          TL;DR: Your answer about what would you choose or at least design if 5.56 and the AR were unavailable was to describe pretty much a 5.56 in pretty much an AR, sorta like how the M1903 Springfield was totally not a Mauser 98 in a silly dress, and 7.62×51 totally isn’t 308 Winchester.

          Sorry if I came off hostile.

          • I didn’t parse it that way, but I’ll answer the question as you read it, anyway.

            I think the 5.45×39 and 5.8x42mm rounds are superior configurations to 5.56mm (though their loads have been optimized for penetration, not terminal effect like 5.56mm). There isn’t really another intermediate caliber with the sorts of bullet choices available to 5.56mm, so that makes choosing an existing load difficult, but both the 7N22 and DBP-10 rounds have exceptional penetration characteristics, so I would keep those in mind.

            An existing platform, assuming the AR-15 never existed… I would be interested in working on advanced Kalashnikov derivatives, then. If I had to choose an existing rifle, I’d say there were a lot of good choices, but that I suspect of the current generation that the AK-12 is the most reliable.

          • Frankly, I am getting a lot of hostility in this thread, and I routinely am accused of being a 5.56mm and AR-15 fanboy. I have never anywhere said the 5.56mm or the AR-15 was perfect, but that doesn’t stop people, I guess.

            I spend a lot of time defending that caliber and the rifle it was designed for because they are good designs (though 5.56mm in particular could be much better) and there’s a lot of market initiative to discredit them. LWRC and Barrett, as just two examples, would love nothing more than to convince everyone that the 5.56mm DI AR-15 is defective and that their products are the solution. If you see more clearly, it’s obvious that the 6.8mm is ballistically mediocre, only offering niche advantages over the 5.56mm (while the 5.56mm offers broad advantages over the 6.8mm), and that while they may be very nice rifles the LWRC Six8 and the Barrett REC-7 don’t perform all that much better than a Colt less than half their price. I don’t wish either of those companies ill (or hell, even the 6.8mm caliber, though it doesn’t do anything for me personally), but I’m not going to repeat their marketing material, either, and when it comes time to give an even shake I’m going to tell people “yes, you’re better off in the long run buying a 5.56mm Colt and a good optic than either of those rifles”. Which doesn’t mean that I’m a Colt fanboy (I’ve made it a point, actually, to run articles on their financial flailing, not that anyone seems to have given me credit for it), it just means that’s what works and is inexpensive.

            If somebody wants to buy a Cadillac just because, I’m not going to tell them to buy a Ford even though the Ford would do just as well, I reckon. But there are a lot of people who think they need to buy a Cadillac because the Ford’s puny .22 caliber round won’t stop the bad guys and its gas system *%$@s where it eats. Since I write for a living, I’m gonna write the truth, which is that the Ford is just fine.

            Like everyone else, I want The Next Big Thing, but when people are trying to pass Cadillacs off as flying cars, I’m going to say that’s wrong, it’s just a Cadillac.

            Does that make sense?

          • n0truscotsman

            What I think is funny is that you are accused of being a “fanboy” because you refute many of the common place stoner-rifle myths that have been pervasive over the past couple decades. Im sure gunshop conversations have become more interesting than they were in the 1990s thanks to the reversal on the general perception of the AR.
            Quite frankly, Im glad that there is a bit of dirt digging when it comes to these myths by not just you, but many others. It proves to me that the POTG zeitgeist is evolving. Because, by golly, I was becoming sick to death of refuting these claims without the aid of the internet. 😀
            Im sure the forums are becoming nasty and brutish, per their usual fashion.

    • valorius

      i’d issue p90 pdw’s with improved 5.7x28mm ss190 ap ammunition- loaded to “+P” velocity such as the 5.7mm ammunition loaded by elite ammunition company.every squad would also have an sdm with a 7.62mm m-21 type weapon.
      -an ex grunt.

      • Kivaari

        The 5.7x28mm is not a suitable infantry rifle. They have a place in special ops, but for general issue it is a weenie.

        • valorius

          im an ex infantryman that says it does have viability as a general issue weapon.

          so there.

          • Kivaari

            So, there, I was an infantry man and a sailor and a cop and a firearms trainer. I like the little P90, but it is unsuitable for general issue. Give it to those people in the rear with the gear. The FiveseveN pistol is not suitable for much of anything.

          • valorius

            what is it you feel that a p90 firing hardened steel core ss190 at 3100fps would be deficient at, compared to a m4 firing m855a1 at 3100fps?

            to me its six one way, half a dozen the other, but the p90 holds 40% more ammo and you can carry about twice as much ammo on your person for about the same weight and mass as 5.56mm

          • Yes, it would retain energy much more poorly.

          • valorius

            if it still has sufficient energy to penetrate enemy body armor at extended range, so what?

            the bullet is a tumbling design, so even at extended ranges, it will cause significant wounds, even with current ss190 ammo.

            honestly, hitting a target at 300 yds is quite easy with a p90, and rapid fire is a dream, it has far less recoil than a m4, and again, 40% more mag capacity. instead of carrying 210rds of 5.56mm, you can easily carry 450rds of 5.7mm for the same weight and space.

            i dont see a downside, at least compared to an m4.

            to me, the downside is in using carbines to begin with, but now that we are…..

          • Penetration would be much inferior to an M4 firing M855, due to the much lower striking velocity and poor sectional density.

            It’s not a terrible idea, but you asked if it was deficient versus M855, and it is.

          • valorius

            hot loaded elite 5.7mm ammo of several types penetrate in excess of the 12″ fbi requirement, albeit at shorter ranges.

            i agree existing ss190 would be deficient, but the bullet design leaves a hell of a lot to be desired. a hardened penetrator and another 300fps of velocity, easily doable, even for the us govt, should yield a very capable round.

            anyway, in the fantasyland where we’re replacing the current kit with something else ‘carbineish’, thats the route id go.

            an m16a4 with m855a1 ammo optimized for a 20″ barrel would be my first choice.

          • That is gel penetration, not armor/barrier penetration.

          • valorius

            yes, gel penetration.

            however, if it had a hardened steel core, as opposed to the mild steel core of ss190, plus the extra velocity, it would still outperform m193 and conventional m855, at least ‘most likely’ it would.

            even current ss190 will penetrate 3/4″ fiberglass hard armor plate fired from an fn five seven handgun.

            ive done lots of testing on the caliber, informally.

          • It would have significantly lower striking velocity vs. M855 or M193.

            Further, you’d need a bigger case, probably about .221 Fireball or .22 Spitfire sized.

          • valorius

            would it? 3100fps at the muzzle would compare favorably to m855 and matches m855a1, right?

            down range the velocity would obviously be lower, but again, almost all combat occurs at 100 meters or less, so who really cares what its velocity is at 300 meters?

            shrug, its interesting food for thought.

          • The BC is much, much lower (about half that of M855), so velocity would drop below that of M855 at ranges beyond 50m.

          • valorius

            no debating that. the ss190 bullet has a .224″ diameter but is much shorter than even m193.

            i dont think it’d be any kind of a factor at typical ‘realistic combat ranges’ though.

          • valorius

            that being said, im not saying its ideal…just better than the m4 firing overpressure ammo…at least in my opinion.

            to me the m4 has too much recoil when fired rapid fire, let alone full auto.

          • Kivaari

            Except in some very close range, with multiple targets the need for full auto doesn’t exist. I never found the M16A1 to have excessive recoil. Most issue M4 carbines have so much junk bolted onto them that recoil is pretty much not an issue. One doesn’t normally fire FA at distances, unless you are moving platoons or squads and suppressive fire is called for. The M249 or M240 fills that roll. Full auto is something people take cover from. Spray and prey isn’t designed to get much more than time to move.

          • valorius

            socom mandated full auto for the m4a1 and hk416. for a reason, yes?

            the p90’s greatest feature is it’s total controllability during full auto fire.

          • Kivaari

            I don’t object to any military M4 or M16 having full auto. I just know that for almost every soldier it just isn’t needed. The gun I used most during the last 10 years of my police job I used the MP5A2 and M4. In using those that FA was fun. I used the M16A1 while in the Army. I know that for most uses FA just wastes ammo with little results in return.
            With the MP5 we had to go through our qualification with the selector set on FA, but only fire single rounds by use of trigger control. Training makes the difference.
            A friend has a FA (dealer sample) P90. It is a neat little gun, and is easy to use on FA. It is controllable. It is well suited for confined space use at short range. It has no punk at distances. Even though most ground combat involving soldier v. soldier combat is short range, the 5.7 just doesn’t have the punch of the 5.56. If you hear so many complained about the under-powered 5.56, just think about the 5.7 with significantly less. Add range, and that little 5.7 bullet just loses too much too fast. Those little 25-35 gr, bullets shed velocity, energy and suffer from wind drift issues. The 5.56 using heavy VLD bullets holds up much better.
            If a soldier could always ensure his target was very close and without barricades maybe the 5.7 would be fine. Like in an urban SWAT situation, with other team members armed with bigger and better rifles. The 5.7 round is cute. It has a place, just not as a standard issue combat rifle.
            Having total FA control means little, compared to a M4. The M4 has little recoil when employed properly. FA for very close range, the only place where the rifle needs FA, is not seriously needed.
            The 50 round capacity magazine is nice, but it is also not as easy to change as the M4. If capacity is a big deal for you, pack a 60 round Surefire.
            The Navy uses some 4.6 HKs for specialized cases. It works for them when they are in contact, muzzle to temple range.
            If I were picking a rifle, I’d take an M4A1 with a 16″ mid-length setup. No burst feature, as that is simple more to break, and is solved with training. Since I don’t have that authority, I’ll just keep my civilian Colt/BCM/Magpul variant. If I could afford a FA version, I’d take it, knowing it isn’t needed, but it is fun.

          • valorius

            i agree that with most platforms FA is of limited utility. However, the P90 is really very controllable in this role. With it’s 50rd capacity and controllable bullet hose effect, it seems to me it’d be pretty effective in a front line close combat role.

            Getting stitched with a burst of tumbling hyper velocity 5.7mm rounds would really ruin your day.

            My favorite AR type weapons are the 18″ Mk12 SPR’s.

          • Kivaari

            Wind drift is exaggerated using a tiny bullet weighing almost nothing.
            Shoot a BB caliber bullet in the HK PDW and it will get there if fired in a vacuum.

          • Kivaari

            How dan the 5.7 drive a bullet that fast, when the M4 can’t do it?

          • valorius

            Elite s4m ammo from a ps90 chronos at 3100fps. it is a lighter bullet than the round the m4 is firing. pretty sure the new m855a1 is over 3000fps even from a 14.5″ m4 too, right?

          • valorius

            btw, elite s4m uses the same fn bullet as ss192/195 and police only ss198. it’s a 28 gr hardened aluminum core spitzer with copper jacket. from the five seven pistol it chronos about 2400fps and hits almost 400fpe energy. from the p90 its about 2800fps and from the ps90 its right around 3100fps.

            ss190 uses a mild steel core bullet weighs 30gr iirc, and is loaded to much lower pressure than elite ammo is.

            so, with a hardened steel core loaded to elite ammo “+P” pressure levels youd end up with a pretty nasty round.

            the ps90 has a longer barrel than the p90, but a lot of the length is a very long flash suppressor added on to make the barrel 16″ civilian legal.

            from the ar57 with 18″ barrel the velocity is even higher. that is also a pretty darn neat rifle.

          • Kivaari

            Keep in mind that the FN 5.7mm firearms were designed to replace pistols and sub machine guns firing 9mm NATO. I have no issue with the P90 being issued in lieu of a SMG. It makes sense in that role. The FiveseveN pistols do not impress me. I guess if you wanted a bulky and awkward handgun in 5.7 go ahead. I’d not buy one simply because of the poor fit in my hand. I don’t know anyone that finds the pistol suitable.
            Personally, I’d take a M4A1 over the BB guns. It is hard to carry a serious rifle while engaged in other activities.
            A PDW works for special circumstances. The little cartridges can be suppressed easily, and that is why some of our SOPs folks use them. I don’t know any warrior that would choose those dinky guns over a M4 or similar rifle. Think about how so many feel about the 7.62mm NATO being the standard rifle round. Listen to them scream about the inadequacy of the 5.56mm. Now put the tiny 5.7mm out there and they will be howling like you never heard.
            Even in Afghanistan gun fighting ranges can be quite close. Even in Israel, where there is quite a bit of desert and open places, and most gun fights take place under 100m, there is a need for something more than the 5.7. I’d like to have one, but I know it is a CQB weapon. I had 7 NFA weapons, and have promoted the use of SBRs in the Uzi, Mini-Uzi and HK 9mm guns. As much as I like those, I wouldn’t want them in a military situation where ranges can vary from in your face to out of sight.
            Like in The Faulkland’s war, the Brits found the most useless firearm was the Sterling 9mm. The special ops, SAS, people chose M16A1s over the SMG or L1A1.
            Most of my training and theater of operation was civilian law enforcement. There I liked the MP5 and M4. One reason for the M4 was soft point expanding ammo did not over penetrate and was effective at short range. It hits with substantially more snooze than the 9mm. But, the trade off is the extreme muzzle blast and flash in confined spaces. A suppressor is needed for the 5.56mm. The 5.7 would probably need one as well. The 9mm subguns are not so bad. We did some training ~15 years ago, We had around 35 members shooting indoors, I used an M4 my partner the MP5. The others had M16s, M4s and shotguns. Indoors the 5.56mm carbines were terrible. I appreciated the men with cans attached. The guns became very awkward, but sure were nice having no flash and no shock wave.
            A PDW like the P90 is great for the people not desiring contact with his enemy. Enough to maybe shoot your way out of contact.
            Handy but under powered. Just like 45 years ago in the jungles of Vietnam, the SMGs just did not have enough power, but they could spray bullets around.

          • valorius

            For long range every squad would have a SDM using either a mk 12 or a m-14.

            Current FN ammo could be considered ‘underpowered’, but there’s no way i’d call tumbling 750+ ft lb energy 3000+ fps velocity 5.7mm ammo underpowered.

            A lot of guys use the caliber to hunt big pigs, and from everything i’ve read it’s very effective in the role.

            Honestly though, military rifles inflict very few casualties. The radio and the squad machinegun are far, far more important than the rifle.

            For the life of me i still cannot figure out why they switched from the M16A4 for front line infantry units. Stupid.

          • valorius

            i remember from previous discussions that you dont like the five seven pistol. I liked mine and had no problem gripping it, but i have fairly large hands.

            I do agree the platform itself could use some significant streamlining and refinement though, if not outright replacement. I think if all the major brands jumped in the 5.7mm PDP business, it would not take long for one of them to make a very practical and popular platform, and one that is not ridiculously overpriced like the FN five seven is.

            Still, a five seven pistol with 30rd mag and loaded with hot elite ammo does provide unique capabilities you’re not getting with a handgun in any conventional caliber firing conventional ammunition.

            I tested various loads against numerous IIIA vests, fiberglass plate armor and polycarbonate bullet proof ‘glass.’ NO other handgun caliber firing civilian legal ammo can come even remotely close to the penetrating capabilities of Elite S4M, Elite T6 or FN SS190.

          • Kivaari

            The FiveseveN pistol can not be made in a size suitable to mist shooters. The over all length of the cartridge creates issues that can’t be over come. Just like a Glock M21SF, it can only get so small, and that is too big for most. The 5.7 pistol with a 30 round magazine certainly isn’t a good choice for concealed carry. It isn’t suitable for packing in a holster in the open.
            Yes, little bullets going fast will poke holes in soft body armor. It’s fine if that is the gun issued to you, even though it doesn’t handle as well as a hammer. As I say, for troops not serving on the front lines, it is OK. I want a better combination that the 5.7 guns out there. That is why the guns were developed. To give soft armor penetration to those soldiers that previously were armed with a handgun or submachine gun. That’s OK for those people, that generally will never hear a bullet passing close. It’s better than nothing. As you know the Russians took another path by making armor penetrating 9x19mm ammo. A bullet having what amounts to an old phonograph needle in a sabot. That works and doesn’t need new weapons. And those guns already in use fit the hands of most people.

          • valorius

            im not so sure about that. As materials improve, and im thinking nano graphene here, the grip frame will be able to be made significantly thinner than is currently the case.

            Give it a few years.

            You can actually make a .25acp that will defeat soft kevlar body armor. Just a matter of bullet profile and construction materials.

            Again though, hardened steel core 5.7mm loaded to elite ammo pressures through the longer barreled PS90 is a whole different animal than relatively anemic FN SS190 fired from a short barrel P90.

            We’re looking at a jump in velocity and power that is akin to the difference between mild range 9mm and thesuper hot subgun only 9mm+P+ that some NATO countries used in their subguns.

            I wouldn’t feel in the slightest bit underarmed with a PS90 loaded up with such ammo. Elite T6 is only made of copper but loaded to the pressure levels im talking about, and can defeat something like 5 level IIIA panels stacked one over the other. So with a steel core, nasty stuff.

          • Kivaari

            That +P+ 9mm ammo wasn’t just for military. We used Federal 9BPLE, a 115 gr. JHP that was within 10-20 fps of the .357 SIG. We used Glock M17 and 19s along with MP5s. Even our practice ammo was loaded to the same velocities. I stopped counting rounds through the Glock 17 at 22,000 rounds. The higher velocity out of the 8.85 ” MP5. So fast that the bullet would not penetrate deep enough. We had to go to heavier bullets in the Speer Gold Dot 124 gr. JHP.
            The military doesn’t use 16″ barrels, as that defeat the purpose, which is to replace pistols and SMGs.
            Keep in mind the very lightweight bullet sheds velocity and energy much faster than a bullet weighing almost 3 times as much.

          • valorius

            The 9mm+P+ i was referring to was the hirtenberger SMG only +P+ ammo. I think that’s the right spelling.

            Ive used the 9bple and numerous other loadings in 9mm, it’s really all i use in that caliber.

            I have even found a few factory 9mm+P+ loads that will defeat SOME level IIIA panels.

          • Kivaari

            I wore a IIA level vest. We did not want our own ammo to be able to penetrate our vests. In the revolver era. after I shot a .357 mag into a test panel. The bullet came out the back about 4 inches wrapped in a ball of Kevlar. It was enough to convince me to put two .38 Special 58 RNL that would cycle up first. Not long after that, Super Vel ammo came out. Almost all of us switched to .38 and found it was much better for street use. Once the powders were tuned to limit flash, it was the better choice. Get there with less, deliver better hits and your vest stops it.
            I used quite a bit of European “Combat” ammo in the Uzi’s. It was noticeably hotter. Shooting at 100m with conventional ball ammo, at SAAMI spec, it took holding high to hit the target. As soon as the combat load was used you could hold “normal” and hit the target. It really was hotter and flatter shooting. I am now old and worn out. If I were back working with youth and health I’d take a 9mm Glock and would be fine with an MP5 or M4. We carried 5 guns for work.
            Either a G17 or G19, a .38 Spl. Centennial, MP5 or M4, M870 with rubber baton and a .22 LR for animal control. We gave up inventorying a sniper. We did have M16A1 and M14 rifles, but those were not issued, just held in reserve.
            It was along way from revolvers and if lucky a shotgun. I pushed for adding rifles or SMGs long before it was trendy. 40+ years ago the most common rifle in patrol cars in my region were M94 .30-30s. Not all that bad.

          • valorius

            level IIA armor, though widely considered obsolete nowadays, will stop a pretty amazing array of bullets.

            I had a 25 year old Second chance IIA panel that i shot to pieces testing all kinds of rounds against it.

            IIA will stop any commercially available .45 ACP, of any configuration, including super hot cor bon 165gr JHP.
            It will stop hot Corbon 135gr+P JHP in .40 cal, as well as 180gr FMJ, probably every .38 special load commercially available, 180gr 10mm JHP, and even some types of hot 9mm+P.

            9mm+P+ of all types cuts right through IIA like butter, as does .357 sig or magnum, of course.

            Lever action .30-30’s and similar are a lot more useful for ‘combat’ than most modern shooters give them credit for. They were afterall the “assault rifles” of their day.

            I’m partial to .357 magnum lever guns myself. Good pairing if your sidearm is a wheel gun. I think al 9mm luger lever action would be really neat too. It surprises me that no one has come out with one for sale in states with strict detachable magazine laws, like california.

            A 22″ lever action in 9mm might hold as many as 20rds. That’d be pretty neat.

          • valorius

            the ps90 barrel is only 16″ because of the long suppressor to get to legal length. And it’s a bullpup anyway.

            I would still stick wit the 16″ in it because it allows you to conventionally mount a bayonet on it. Any shorter, and that would be a problem. But i would actually use a standard legnth flash suppressor and add an inch of actual barrel. That would give even more velocity as a nice side bonus.

          • Kivaari

            I can’t envision bayonet fighting with a P90. My Uzi had a cute bayonet, that were so often stolen, that they were even taken out of Israeli service. A bayonet on any of the sub-guns was for prisoner herding, not serious combat.
            The prime reason for bayonets today is to have a wire cutter the troops wont throw away.

          • valorius

            bayonet fighting with a ps90 would be no different than doing it with a british L85 bullpup, which was done during the Iraq war by british forces.

            They had an epic bayonet charge in Basra early in the war.

          • Kivaari

            S90 has a 16 inch barrel to make it comply with NFA ’34 and GCA ’68. They don’t have sound suppressors as standard. The flash hider isn’t a big deal. I’d have a PS90 SBR if it wasn’t such a hassle. The pistol is just not worth owning. Only handguns that fit my hand get any seriously considered. That is why I have trimmed my pile to 9mm Glocks, J and K-frame S&Ws. Since I don’t have much life left to use up I have a couple ARs. It doesn’t make much sense to have too much to leave the wife to deal with after I kick over.

          • valorius

            yes i know, thats what im saying. The factory flash (not sound) suppressor on the PS90 exists only to make the barrel length a total of 16″.

            So on the hypothetical military PS90 i’d ditch the 3″ long factory suppressor and replace it with a standard length M16a2 style flash hider, but keep overall barrel length at 16″. This would effectively give about another inch and a half of rifled barrel while maintaining the same OAL as a current PS90.

            That would add about another 100fps of velocity vs a standard P90

            Your opinion of the FN57 pistol is noted, however, i liked mine and could “gong” steel plates at 100yds all day long with it.

          • valorius

            i seriously doubt a 5.7mm ss190 sheds velocity anywhere near as fast as any 9mm pistol bullet does.

          • Kivaari

            Lightweight bullets with the BC of the 5.7 is intended to give up range. The early plastic core rounds were specifically designed to do so. An aerodynamic VLD bullet with proportional weight outperforms the little ones. The 9mm has more retained energy at distances. Neither one is suitable for long ranges. They are PDWs for in-your-face contact. I’d take a P90 in addition to a pistol, if I was an REMF. I was such in both the Navy and Army. In the rear with the gear.

          • Kivaari

            You can make tiny solid bullets driven fast enough to go through 0.50 inches of steel. You can make .22 bullets made of lead and copper go through steel plate. That can do it at 50 yards, but not at 100 yards. Velocity and weight makes a huge difference. That is where standing a few feet from a stack of armor doesn’t translate into 100-200m hits. What can the best 5.7 from a P90 (not PS90) do at 100 or 200 m? I suspect that an M4 carbine having a 14.5 ” barrel will do much more damage than any bullet from a 5.7 can do.
            Yes, the 5.7 can replace the 9mm SMG as a defensive close range round. If it could do what the 5.56 can do, we would see more of them in service. I suspect a close range hit in modern military body armor with a ceramic plate would stop it easily. If a .22 Mag firing a 25 gr. bullet that pokes holes at contact distance, will be just about useless at 100m. What is wrong with the 5.7 is it can’t deliver a 62 gr. or heavier bullet at a meaningful velocity. A little blow back action just can do that. If it could, we would have had them decades ago.
            Shooting a steel plate at 400m (by laser) the 5.56mm leaving the bore at a higher velocity doesn’t do as much damage as the 7.62mm.
            It is just basic physics.
            I can hear the screams from the battle fields already. NO military is going to issue the 5.7 in any package designed to replace the existing 5.56mm rifles and carbines. Every leading edge – sharp tip of the spear – soldier will want his 5.56 carbine back. If you want a longer range gun, use 77 gr. OTM loads. Lower velocity that holds up well past 300m. Take a steel plate to the range.
            Set it up at 100m/y and shoot it with whatever 5.7 load you want, then use the 5.56mm M855 or the heavy loads. Look at the dimple the 5.7 leaves compared to the 5.56. Then take a 7.62x39mm with a steel core and it doesn’t do much.

          • valorius

            i wont say that a 5.7mm of any kind does as much damage as a 5.56mm, because it doesnt. I will say it does “enough” damage, and can certainly cause 9mm or 45 JHP type damage, but with much, much greater armor penetration and long range capability due to the much flatter trajectory of the high velocity spitzer 5.7mm uses compared to 9mm pistol bullets.

            NATO did a lot of testing of SS190 fired from the P90. It’s described in general terms on the wiki page, or in much greater detail on other sites if you want to do a little google fu.

            Obviously performance with a hardened steel core variant of the SS190 loaded to higher pressure and fired from the longer barrel PS90 would have dramatically greater armor penetrating and wounding effectiveness though.

          • Kivaari

            What I am concerned with is not the civilian use of a long barreled PS90. I think if you want one so configured that’s fine. The whole PDW concept using the 4.6 (4,68 etc) and 5.7 was not worth adopting. There are almost none in service in any numbers beyond trials quantities. I would like a P90 SBR for FUN. If I wanted a small entry gun for civilian police use, I loved the MP5 I was issued. I had two HK94 SBRs. Loved them for fun. I would use them in a crunch, but know the M4 carbine in SA, is a superior firearm for anything I would need. Today or in my youth. I loved my Mini-Uzi as it folded to 14″ OAL. I could hit an 8×8″ square at 100m. I could hit a man-sized target at 200m easily. But, firing tracers shows what happens to pistol rounds at such distances. Using IMI tracers, the bullet would get to about 90m and start a very perceptible nose dive. Now the 5.7 flying faster would get there flatter, but it is going to run out of steam fast. When NATO tested the PDW concept, they wanted 200 performance. It just can’t do much at that range. The Germans had a fit and wanted the 4.6 to be standardized, except it was even less impressive than the 5.7. When all was said and done, NATO decided the concept was not viable or worth the effort.
            So what did armies do? They tried a few and put them into storage. The trend has been to use 5,56mm in the west, the Russians use both 5.45 and 7.62 rounds. Even having troops armed with SKS carbines until recently (not just parade troops).
            Our military uses the M16 variants. A Mk18 with a can, if a good weapon, but it doesn’t have much punch out of the 10.3″ barrel. It does the job of the 5.7 better. The M4A1 is great. The Mk12 is great. A 5.56mm 20 free-floated barrel with proper ammo works well. One USA Army shooter killed around 50 Taliban in one night. I believe his name was McDonald (memory lapse) he was later killed in Iraq. That was with a suppressed rifle. Most all were one shot kills. Tactics and balls made it possible.
            I don’t like adding aftermarket parts to make a gun operate with ammo that exceeds the original design parameters. It’s like adding a lift kit to a 4×4 truck. The original design works better.
            I get the idea there is an inverse ratio of height to intelligence.
            Not saying that about you playing with heavier springs in the FN. I just wont do it. I will change to a better aftermarket trigger, as the AMU has done.

          • valorius

            Really, NATO was about to adopt the P90 and 5.7mm, but the germans threw a fit that their 4.6mm lost out and got the whole program killed. There are some NATO forces that do use the P90 in small numbers though. A lot of elite police and body guard agencies use it too.

            I personally think that the military p90 with FN ammo is underpowered. The long barrel (but still super compact) PS90 with hot “+P” type ammo is an entirely different animal though. Even with the crazy long factory flash hider (meaning there’s really proably only about 12.5″ of rifled barrel or so) you can get 3000+ fps velocity with “+P” 5.7mm using the standard FN 28gr OTM bullet.

            With the barrel config i just described, velocities at or near 3200fps should be possible.

            I think conventional subguns such as the MP5 are obsolete nowadays because of their poor performance against personal body armor, and the proliferation of dirt cheap police trade in armor on ebay and similar sites.

            You can get IIIA armor that will stop virtually any 9mm on the commercial market for about $200 bucks, and sometimes half that price.

            I have a US Armor IIIA, a Safar

          • Kivaari

            It’s hard to get more velocity out of the carbine/SMG or pistol. Pushing the velocity up increases pressure. They get a new shoulder as the pressure is too high. I tried this 30 years ago with 7.65mm Luger. In the Spanish M600 it worked fine with 9mm. We made a .30 caliber barrel, its a simple job, but even with under powered commercial ammo, the shoulder moved forward. In a SIG P220 in 7.65 the ammo was too weak. But when a 9mm barrel is installed you need a heavier recoil spring. Locked breach system v. blow-back. The P90 is blow-back the pistol is slightly delayed blow back. FN used a cleaver and simple retarding method. If someone would do the same with .22 magnum, I think you would finally see one that works.

          • valorius

            Ammo already exists in 5.7mm that develops the velocities i’m talking about though.

            Check out Elite ammunitions T6 and S4M loadings.

            But i will again concur that factory FN ammo can fairly be termed underpowered.

            Stronger recoil springs are typically installed by P90 users that shoot elite ammunition.

            I’ve used their Protector I (40gr Vmax at 1900fps from the pistol), Protector II (50gr ballistic top at 1800fps from the pistol) and S4M (28gr OTM at 2400fps from the pistol).

            It’s good high quality ammo, i never had any pressure related problems, or any problems of any kind with it.

          • Kivaari

            You might read some of the websites dedicated to the 5.7mm. With rare exception the 5.7 get panned as not being effective in the real world. The best loads are said to leave wound tracks less severe than the 9mm NATO FMJ. Now, if a round can’t do what 9mm ball ammo does, and everyone says the 9mm is inadequate (I disagree) then how does the 5.7 have a use?
            I would not buy what is essentially a high-priced toy. From what I can glean from the comments is nearly every agency that bought 5.7s all have dropped it due to its failures.
            No one can make the round break Newton’s laws.

          • valorius

            Quote from brassfetcher:

            “As tested, both 5.7x28mm cartridges offer lethality that is on par with or slightly greater than a .45ACP
            230gr jacketed hollowpoint. This is accomplished through an intelligent usage of the pitch/yaw cycle inherent
            to any spin-stabilized projectile – the nose of the 5.7mm bullets travel through the first 2” of ballistic gelatin in
            a nose-forward orientation, which minimizes drag. For reference, the calibration BBs fired into these blocks
            are 0.177” commercial airgun BBs that penetrate the first 1.7” of gelatin, impacting at 575 ft/sec. As such, the
            very impressive amount of kinetic energy lost by most expanding bullets in the first few inches of penetration
            have little or no effect on the human target and actually decreases the effectiveness of expanding ammunition
            in incapacitating a target.
            Conversely, the FN SS-195 and the Elite Ammunition S4M offer performance quite similar to the tested
            .45ACP, with considerably lower recoil and ammunition weight, coupled with a significantly higher weapon
            magazine capacity. We feel that the Elite Ammunition S4M can be seen as a “+P” version of the very effective
            27gr 5.7mm FMJ and we have no qualms about recommending this cartridge as a feasible replacement to the
            more conventional .45ACP handgun, for use against human attackers.”

            That is from an expert who’s actually gel tested the ammo, unlike the dentist roberts, who NEVER had tested the ammo at the time he made all his assinine comments about 5.7mm ineffectiveness.

          • Kivaari

            In the professional journals the common opinion is the 5.7 doesn’t deliver a wound close to 9mm, .40 or .45. With a few exceptions all the stuff I read about it, reports poor performance.
            I can see civilian police in Europe using the 5.7, It took them long enough to get away from 9mmK and 7.65x17mm.
            I will stay with the 5.56mm in a more conventional platform.

          • valorius

            the only expert that has blasted the 5.7mm is the dentist, and he NEVER even fired, let alone tested one, when he made his negative comments about the caliber.

            He is a fraud.

          • Kivaari

            Look around. There are quite a few negative studies from the experts. Even the medical analysis of the Ft. Hood shooting is revealing.

          • valorius

            Actually, the Five Seven performed with brutal effectiveness at fort hood.

            THREE soldiers attacked the terrorist at point blank range when he first opened fire. One throwing chairs, another charging with a table, and an orderly that tried to grab him from behind.

            All three were INSTANTLY dispatched by center mass hits from FN SS192 ammunition.

            When the first officer engaged the terrorist he hit her in the knee with a single round of SS192. It completely shattered her knee, she is still permanently disabled, and has required over a dozen surgeries. And she immediately dropper her gun. The terrorist walked right up to her and kicked her gun away.

            The terrorist was only stopped when his five seven jammed.

          • valorius

            the only expert that has denigrated the five seven is the dentist…and he never even tested the round at all.

            His opinion is far outweighed by both it’s performance at fort hood and the extensive ballistics gel and high speed photography testing done by brassfetcher.

            Anyone with any sense knows that getting hit with an almost 1″ long tumbling projectile at anywhere from 2-3000fps is going to be a very unpleasant experience.

          • valorius

            my favorite is the story that the dentist and other 5.7 mm detractors throw around where the guy gets hosed with 5.7mm and begs the cop to stop shooting him.

            They make it sound like a failure….the guy immediately ceased all hostile action, and died at the scene.

            May all righteously fired guns fail in the same way! LOL

          • valorius

            From wikipedia, but it’s described in far better detail in the court transcripts:

            Army reserve Captain John Gaffaney tried to stop Hasan by charging him, but was mortally wounded before reaching him.[27] Civilianphysician assistant Michael Cahill also tried to charge Hasan with a chair, but was shot and killed.[28] Army reserve Specialist Logan Burnett tried to stop Hasan by throwing a folding table at him, but he was shot in the left hip, fell down, and crawled to a nearby cubicle.[29]

            That’s three determined attackers, 2 of them trained soldiers, all at nearly hand to hand combat range, and all three instantly stopped.

            Several witnesses testified that hasan was able to lay so much fire with his five seven pistol that they thought it was multiple attackers with M16s.

          • Kivaari

            Any gunshot wound through the heart and associated blood vessels (aorta and pulmonary) usually results in quick death.
            There is a report on the Hood shooting, that reaches a different finding. A hit in the knee by pretty much anything like a 9mm-.45 will destroy the knee. Bone strikes, with a 5.7 should cause a mess. I treated a man shot in the arm with a .22 LR pistol. It was a very nasty wound, nearly breaking the bone completely. The bullet left fragments in a 2″ diameter area, intermingled with bone chips. Another case where I worked the scene, the victim was shot in the knee, a contact wound, from a 12 ga. It took out the knee as expected, but what was weird was that even though tissue and blood was ejected from the wound, no pellet left the leg. The wall was sprayed with material, and I had to lock the kitten in a bedroom, as he was wanting to eat the flesh on the floor. The point is bullets are not predictable. I would expect any wound with an expanding bullet would kill. There isn’t anything much more “expanding” than a birdshot load from a shotgun. To find none of the 1.25 ounces of shot in the wound shows how predictability is NOT so predictable.
            The bulk of the tissue injuries leaves 80% of the victims alive. Those cutting a major vessel usually kill. A stab wound or GSW to the heart can be survived if it doesn’t clip nerves and the hearts blood supply.
            No one is saying the 5.7 wont kill. It will, and has done so. What I know from the medical journal, is the hits in tissue w/o a bone strike on entry, were less significant than the common pistols.
            I am not making this stuff up. But you wont be able to convince anyone that the 5.7 is suitable for typical combat in a military setting. A citizen shooting expanding bullets at close range, and they hit a vital organ or nerve cluster will likely kill the victim. A 5.7 is not and will never be a good 200m combat arm.
            Those little bullets simply don’t hold up at distance. It’s basic physics. Considering the many people that say the 5.56mm is not a good round for combat would really find the 5.7 to be a toy.
            Pack you gun. I’ll pack mine. I’ll take a 9mm over a 5.7mm in a handgun.

          • valorius

            the beauty of the 5.7mm for military use is that it doesnt need an expanding bullet, as all the military loadings are tumbling bullets. The SS198 LEO duty round uses the same mechanism. SS192/5/8 all use the same hardened aluminum core copper jacketed Otm bullet. It’s .85″ long, so when it tumbles it does quite a bit of damage.

            A 9mm with JHP is an excellent choice as well, but 9mm ammo is 40% heavier and bulkier than 5.7mm ammo, so you can carry 40% more ammo for the same weight/volume. 9mm also kicks considerably harder than FN 5.7mm ammo does. Full pressure elite “+P” 5.7mm ammo kicks about the same as typical 9mm 115gr range ammo.

            I’ve owned and carried many 9mms for many years, and i do like them. A lot. But the 5.7mm does have some distinct advantages, especially when fired from a carbine and when facing an opponent wearing body armor.

            I sold my five seven during the obama gun ban scare, and made about 500% profit on it and all the ammo i had, so i don’t even own one any more, but i REALLY liked the concept, just wish the five seven pistol was a better platform.

            My dad (ex philly undercover narcotics cop) and brother both own PS90’s. Shooting one is like shooting a .22LR rimfire rifle, when it comes to recoil, precision, and rapid fire ability.

            It’s a small bullet, but small things moving fast and tumbling through their target can still do terrible things.

            It’ll never happen regardless, the US switching to the PS90 for front line troops, but it’s been a fun discussion. 🙂

          • valorius

            probably the most prestigious unit to use the five seven is the UK Queen’s royal bodyguard unit.

            The USSS used P90’s for several years too, but i think they’re using M4’s now.

          • Kivaari

            The HK 4.6 was said to be much poorer performing than the 5.7.
            I don’t judge how good a firearm is based upon what police agencies by and field. Police often pick poor weapons. From what I recently read, no one knows if the 5.7s are still being used by US police. The general comments were it performed so poorly that they withdrew them from service. The whole PDW concept has drifted into obscurity. Your ability to knock plates with your 5.7 is not really important. Most shooters can do so in slow fire. When needed in a hurry almost no one can hit much with a gun too large for the hand.
            When I went back to police work, the department issued Glock M21s. They bought me one, I showed the chief why it would not work for me. We did some shooting, where I could hit just about anything I wanted to while using slow fire. I told him, and showed him why the gun was unsuitable for general issue. When we left the range, he had me order a G17. It wasn’t long after that, that the whole department was rearmed with G17s or G19s. When he saw why the others were not doing well with the G21s, my advice was taken. Individual agencies often have a small but vocal number of people that just have to have a .45. I warned lots of departments to not just go with the on-staff gun guys opinion, as they are shooters and just don’t care why others don’t do as well as he does himself. When entire departments get stuck with over-sized handguns or shotguns, they usually can’t afford to rearm with a better choice for a couple of years.
            The .40 S&W was an attempt to fix that problem ( as was the .45 GAP ). Getting the big bullet into a better-sized pistol sounded good. We now see the .40 fading into history, as police return to the 9mm. It really is a better choice. The 5.7 round cannot be made in a package suitable for general issue. The cartridge is just too long. so even a single stack version would have poor ergonomics.
            5.7s in the P90 is a cute package. I’d take a 9mm. I never encountered a suspect wearing body armor. It happens, but that’s why we train with a double tap to center mass and others to the head. It is all solved if you pack a 5.56mm M4 or Ruger Mini 14. Cops can’t have special gear that can’t do the job every day as opposed to having them when the fan gets hit. Tactics overcome most of the issues.

          • valorius

            My five seven didnt fit my hand too badly. Again, not everyone is the same.

            At any rate, in gel, the fact is that there are 5.7mm rounds that brassfetcher has stated are superior to .45 acp JHPs.

            So not too bad.

            I used to open carry my five seven when i was repossessing in really bad neighborhoods in Philly. I liked knowing that with just one spare mag i had the firepower to take on a north philly drug gang…..those guys got REALLY mad when you took their hopped up mercedes. LOL

          • valorius

            FN five seven SS195 from the five seven handgun hits 2100fps. The same bullet is loaded by Elite Ammunition company, and achieves a velocity over 2400fps from the pistol, over 3000fps from a PS90, and over 3100fps from an AR57.

            The ammo exists, it’s available for purchase, and has been extensively gel tested by brassfetcher and others…it’s not hypothetical. 😉

        • valorius

          seriously, steel core impoved ss190 at 3100fps will do anything m4 launched m855a1 at 3000fps will do….and in a much more compact package that holds 40% more ammunition.

          almost all casualties are caused by the radio, not the rifle….the p90 would be perfectly fine in an infantry role.

          • Kivaari

            There is no way a 25-35 grain bullet will perform adequately at any distances beyond 100m. Yes, casualties come from communications calling in supporting arms. I like the P90 as a weapons for those that are not riflemen. With troops engaging targets at 300-400 m the little bullet just doesn’t do much. At 50m it will do the job formerly done by pistols and SMG. It is a gun and ammo combination for support troops. Those that say the 5.56mm NATO M855 is not a good enough round, just think what they would get with that little 5.7mm.

          • valorius

            almost no infantry combat occurs outside 100yds, but i can tell you that even existing ss190 will defeat multiple layers of stacked level iiia vests at 100yds, and will still cleanly penetrate a single iiia vest well in excess of 200yds.

            fn loaded 5.7mm ammo is pretty wimpy, so an improved ss190 with a hardened steel core would be a whole lot more effective.

            there is simply no realistic scenario when it would not be satisfactory based on current us doctrine for ground combat, which is to establish contact then keep your head down while air power and arty devastate the target.

            for room cleaning and the like, which is very prevalent in the war on terror, the p90 is almost perfect.

          • Kivaari

            Why are our soldiers engaging Mujis at 300-400m? If the M4 or Mk12 is not good enough according to some the 5.7 will deliver less. All of the other assets are not always available. If you can get air or arty, your rifle becomes more important.

          • valorius

            afghanistan is an anomaly. numerous studies have shown almost all infantry combat occurs at a range of 100yds or less, dating back to wwii.

            but remember, i did say my first choice would be to go back to the full length m16a4….which probably aint gonna happen in our lifetimes.

          • Kivaari

            The tiny bullet loses velocity and energy too fast. There are times when a rifleman needs to hit a 300-400 m. P90 would make a great SWAT weapons for extremely close range. The Navy even uses the HK 4.6 mm BB gun for the right circumstances. They just do not have enough power. A 25-35 grain bullet compared to a 62 or 77 gr. bullet at 300-400 m just doesn’t have much snooze.

          • Kivaari

            What? The 5.7mm was designed to replace 9mm pistols and SMGs for ranges of 200m or less. Even the 9mm pistol retains more energy at 400m. What 5.7mm gives the 3100fps from the SMG or pistol? FN says it does 2350 out of the P90. The 5.7 pistol is well under 1800 fps. Short and sweet, the 5.7x28mm can not do what a 5.56mm NATO can do. The 5.56mm starts out faster with a bullet 2.5 times as heavy. NO 5.7mm can deliver much.

          • valorius

            im not talking about fn factory ammo. the ballistics im describing are obtained by several loads from elite ammunition company….which i already mentioned.

            elite s4m from ps90, 3100fps, approx 700fpe energy….way beyond 9mm ballistics.

      • LilWolfy

        Not sure if serious.

        • valorius

          read the rest of the discussion and decide. 😉

  • n0truscotsman

    Hmmmm, Nathan tackling one of the most coveted small arms cartridges in recent history and forum fans coming to throw in their two pennies?–This-is-gon-sWM8.gif

    (I needed an excuse to use that again. Love it)

  • r

    6.5 grendel

  • The problem is trying to stuff a new and more effective cartridge in an old rifle. What is needed is a new rifle in a new cartridge.

    • Modern 5.56mm ammunition is much, much better than M855. The AR-15 has always been a pretty reliable gun, but now it’s more reliable than it’s ever been.

      I think, though, that were I in charge of things I wouldn’t be content to sit on those laurels, and I’d push for technological advancements in ammunition weight and effectiveness, and for weapons compatible with that new ammunition.

    • Alucard

      I propose a semi-auto only rifle that holds 20 rounds of 8mm mauser.

        • Alucard

          Its no contest 8mm mauser is vastly more deadly than 5.56.

          • It’s weird then that 5-7 riflemen armed with AR-15s can achieve fire superiority over 11 riflemen armed with M14s in 7.62mm NATO.

          • Alucard

            In which fantasy world was that?
            5.56 takes more rounds to kill a man period, sure they may have 30 rounds but what does that matter if it takes 4-6 to kill a man?
            1 accurate shot of 8mm mauser center mass will do more tissue and organ damage that 1 shot center mass with 5.56.Just as .25 acp will do less tissue and organ damage than .40 S&W,I would expect better knowledge from a gun blog writer.
            Do you also believe the myth that .22lr will bounce around in someones head?
            More powerful round equates less shots needed to kill armed combatants,that can only be a good thing.

          • Andrew

            5.56 does not take more rounds to kill a man than any other rifle round I have seen used for that purpose. Except on MW3. 5.56 is doing the job quite effectively in more places than I can pronounce.

          • wojtekimbier

            “it takes 4-6 to kill a man”– in which fantasy world was that? Or, rather, which CoD game have you played? I would expect an internet commando like you to understand fragmentation. I would also expect an internet commando to understand suppressive fire (99.9% of all shots fired), the difference between killing and disabling a combatant (who, if alive, has to be taken care of), the much lower weight of soldier’s equipment armed with 5.56 (who often has to walk on a patrol for days). I would also expect you to know that .223 has much lower recoil and is much cheaper which means soldiers can get better training. The 8mm might be better for hunting or do more tissue damage but you have to be ignorant to think this is what matters in a modern war.

          • Soap McTavish

            You need to put on “Stopping Power” in the create a class menu.

            Don’t for get extended clips, too.

          • The world that doesn’t have any anime vampires in it.

          • Kivaari

            It isn’t one cartridge over another cartridges performance that makes one better than another. The 8mm Mauser is a grand cartridge. That doesn’t mean it is a superior combat system. I believe Nathaniel was discussing how a squad of men using AR15/M16 rifles can deliver, more effective performance by using a better rifle and movement. The lighter and easier handling rifle with 30 round magazines, need fewer and easier magazine changes. The AR15 having less weight of rifle and ammo allows the smaller force to out perform those having heavier rifles with 20 round magazines. Those M14 rifles are harder and slower to swap out magazines. That gives the men armed with the varmint rifle a superior system.

          • Seras

            Alucard, tough luck debating this guy. In his world, nothing beats the M4, not that it stops him from claiming to be neutral. If something outperforms the M4 at all, he will take the slightest M4 “advantage” regardless of whether or not it is meaningful or relevant. If something is superior to his M4, then he’ll find some mitigating factor, no matter how small or irrelevant and then claim that makes the M4 superior. If comparing against some other weapon which has multiple iterations or variants, he’ll make sure to cherry pick the variant which stacks up the worst. If the M4 loses at anything, there’s something that can be claimed that might be objectively true in some twisted reality which makes the competition inferior in one regard, and therefore makes the M4 wholly superior. If the M4 wins, it’s because it’s the best. If the M4 loses, its competitor actually has some fatal flaw in some obscure way which makes it irrelevant and therefore means that the M4 is still actually better in spite of what anything else says.

          • Whatever lets you sleep at night, I guess.

          • Alucard

            I have come to realize a lot of people think in a similar manner regarding the M4/M16/AR-15 as he does.

          • LilWolfy

            It doesn’t work like that. The Army already knew this with the Fort Benning trials when the AR15 was being looked at more seriously. In maneuver warfare, the AR15 is the gun to have over any of the legacy battle rifle performance cartridges for a number of reasons.

            1. Firefights aren’t won entirely on making hits, since you rarely have a clear sight of the enemy most of the time anyway.

            2. He who fixes his opponent first, then maneuvers on him or destroys him with other means wins.

            3. These things take time, and time = ammo in the world of firefights.

            4. He who brings the most ammo has a decided advantage over his opponent.

            The main rounds that count are often fired at close range, where any high powered rifle cartridge will kill effectively. In addition to precision fires from designated marksmen, fire superiority and effective actions on the objective are what kill enemy.

            In my experience, the belt-fed guns do most of the fire superiority, while hooahs with carbines can maneuver easily. You reduce your maneuverability and ability to keep up the fight if you regress to the ill-conceived concept of the battle rifle.

        • Dolphy

          That’s just like you.

  • Just curious: How many views has this article received so far?

  • Evaris

    I’ve got to ask, any chance for such an in depth look into the 6.5 Grendel as a comparison? This really is an awesome article.

    • this is from the “a case against GPC” article” that Nathaniel wrote:

      “There are numerous problems with the 6.5 Grendel, first and foremost being its unsuitability for military applications. Beyond (valid) concerns about the cartridge’s extreme shoulder angle and lack of case taper, the case itself does not have enough internal volume to accept tracer or steel-cored armor piercing projectiles, except with the lightest bullets. Thus, it cannot fulfill the role of a GPC, as it is not a suitable military cartridge. Further, the 6.5 Grendel provides low levels of performance with factory loads, only achieving its much-touted velocity and trajectory with delicately loaded handloads using very slow-burning and often compressed powders. For field purposes, it is a 7.62×39 with better bullet selection.”

      • Evaris

        Could you link me the article? I know I know nothing of military bullet design, but.. I have to ask why on all of that. I want to understand why an extreme shoulder angle is bad. Why does internal volume prevent the loading of tracers or steel core ammunition aside from “extremely light”? And what constitutes “low performance” of factory loads like Hornady A-Max? I’m curious. DX

  • GearHeadTony

    I was looking for the comment section, but all I found was the angry fanboy section. Me and my 6.5 Grendel will be over here trying not to laugh.

  • WV_Hunter

    I think you need to look up WV’s centerfire vs rimfire caliber requirements before you include it in your “study”. The 25 or larger caliber applies to rimfire.

    • Good catch! I did remember that incorrectly, thank you.

  • Evaris

    Just read it.. and still not understanding, I’m afraid.

    • Hi Evaris,

      Thank you for your kind words about my article. I will try to answer your questions about the 6.5 Grendel.

      The 6.5 Grendel has slightly less case taper than the 7.62 NATO, which itself has not as much as I’d like. The shoulder angle is 30 degrees, which is sharper than the 23-degree shoulder of the 5.56mm or the 20-degree shoulder of the 7.62mm NATO. These are not damning to the cartridge, but I have reservations about how they affect extraction and feeding, respectively, in automatic weapons.

      As for the concern about lead-free/steel-cored/tracer projectiles, those take up more volume than lead-cored projectiles, and extend into the case more. Because the 6.5 Grendel already has a short, fat case, this significantly reduces performance if the use of those projectiles is required. To illustrate how dramatic this can be, a while back I rendered a 6.5 Grendel round utilizing a lead-free tracer bullet with the same amount of compound as (IIRC) the 6mm SAW tracer. See below:

      Ballistically, though, the Grendel is much superior to the 6.8 SPC. See this comment I made for more information.

      • Evaris

        Thank you for the information! Though this pushes my curiosity a bit further, so I hope it’s okay for me to ask a couple more questions.

        1. With tracers, is the same true with a lead core being present? Or am I misinterpreting this?
        2. With steel core – what difference might there be if you were to replace steel with a high strength copper alloy like C71500, C86300, or C17200/ or a high strength cobalt alloy for greater density? Or just sticking to Tungsten for high penetration rounds?

        • Evaris, you’re welcome to ask as many questions as you like, though I cannot guarantee I will be able to answer them all. Also, feel free to email me at the address in my author’s description.

          1. Essentially, the 6.5 Grendel suffers more from low density projectiles at its intended weight (~120gr) than other cartridges because of its short overall length. So whether you are stuffing a bullet made of steel, aluminum, tracer compound, or even explosive into the case, its performance will suffer. Have a low enough density bullet, and you can see dramatic drops in performance. However, the 6.5 Grendel performs very well with lead-cored OTMs such as the 123gr Lapua Scenar.

          2. Tungsten isn’t really practical as a standard infantry bullet material, due to its cost in solid form and its temperature instability in sintered form. Copper alloys improve on the density of steel, but only marginally. As an armor penetrator, too, steel is hard to beat.

    • check out his latest comment on this article.

  • Lothaen

    Excellent study of the cartridge. I am once again re-affirmed in my
    belief that sticking with and mastering 5.56 is not the ballistic chain
    around my neck as it is often purported to be.

    Keep in mind, we civilians are not tied into the constraints of MK 262 and now with
    Sierras 69 and 77 grain tipped match kings hitting the market, we may
    have even better ballistic options present in the platform.

    IIRC the 69 grain TMK
    approached the BC of the untipped 77 grain stuff!

  • Dear 6.5 Grendel fans,

    You and I haven’t always seen eye to eye. I think your favorite round is over-hyped and designed with the wrong priorities in mind.

    However, this time I feel we can work together. Below are ballistic charts for the 6.5 Grendel as compared to the 6.8 SPC. These figures are as fair as I feel I can make them (for reference, the velocity of the 6.5 Grendel is taken from here). They show the significant ballistic disadvantage the 6.8 SPC is at versus the 6.5mm. I not only give you permission to share these graphs, but I encourage it. Some of the claims about the 6.8 SPC’s performance have left me scratching my head, and I’d like to clear everything up for my readers. So go out into the wide Internet and share these as much as you want:

    Some interesting facts about these ballistics:

    1. The 6.5 Grendel exceeds the energy of the 6.8 SPC at a mere 90 meters.

    2. The 6.5 Grendel exceeds the velocity of the 6.8 SPC at 250 meters.

    3. The 6.5 Grendel as a nearly identical trajectory to the 6.8 SPC out to 600m, and a significantly better trajectory beyond that range.

    4. The 6.5 Grendel stays above transonic speeds for 120 meters longer than the 6.8 SPC (reaching 1,451 ft/s at 630m versus 510m).

    5. The 6.5 Grendel stays supersonic for 200 meters longer than the 6.8 SPC (reaching 1116 ft/s at 890m versus 690m).

    6. The 6.5 Grendel bucks the wind much, much better than the 6.8mm SPC.

    7. The fragmentation ranges of the two rounds are almost identical, if a threshold of 2,000 ft/s for a BTHP is used. Both slow down to that speed by 260m.

    • Kivaari

      Now plug in a .30 caliber bullet and see how poorly it does against both of the 6.5s.
      Instead of buying a new 6.8, I think I’ll sink the money into some better 5.56mm ammo. Except for zeroing, I have what I need. Although a friend has a storeroom filled with 6.8 ammo no one wants. Maybe I can get a deal.
      I am surprised at the contentious responses to the work you did. I appreciate it, as it firms up what I was thinking of doing. No need to buy another upper and special magazines. I don’t quite get why so many people resist facts – flat earth society?

      • Andrew

        Mainly because they don’t understand physics, never studied medicine, and most haven’t carried ammo uphill. I suppose I’m a 556 fanboy, though.

      • I’m not sure. I wish I could say I was disappointed, but I’ve been saturating myself in the 6.8 SPC fandom for the past two weeks in prep for this article, and I expected nothing less than this response.

      • Hyrdr

        Please share your information of the friend with 6.8 ammo he cant get rid of.

  • hikerguy

    I would like to thank all of you for a very entertaining discission thread. I will admit that I know very little about ballistics but have learned a great deal through reading this. Thanks to Nathaniel F. for your posts. I enjoy them and find them both informative and fun to read.
    As far as the various combat rounds used in the AR platform goes (I am honest to say I have never owned, shot, or even held one) the military has decided to stick with the 5.56 so the debates over these rounds as combat rounds are fruitless. I would suggest using a cartridge that meets your needs and don’t worry about others opinions. All are good rounds, but you make trade-offs when choosing one over another. Perhaps Tony Williams was right when he said that a new GPC would ideally be one of 6.5 caliber, but will have to leave the AR magazine well for one slightly longer to fit the thatl round, but I just do not see that happening yet.
    Oh, and one other thing of note I noticed……I must disagree somewhat on the M4 Sherman being the superior tank of WW II. I mean, it was called the Ronson for a good reason. But, we could produce it in greater numbers, which is a quality in itself.
    Now that I have enjoyed being up reading this since 4:05 AM, I can go sleep off my insomnia now since I have a day off. Have a great one folks. Gotta love the firearmblog.

  • Biguth Dickuth

    As an armchair Wicki Warrior, having read all about Grendal, 6.8, mk 262, + etc, etc, and reading these opinions I have to chime in that the Chinese 5.8×42mm seems to approach the ideal. 71gr at 3,000 ft/s 5.8mm must have efficient BC and hit hard at range with minimal drop and drift. Why isn’t it being researched/discussed?

    • My father was Naughtius Maximus. 🙂

      The Chinese 5.8x42mm is optimized for penetration at long ranges, while maintaining basic suitability for infantry rifles. The current DBP-10 loading uses an armor piercing steel core. The projectile appears to have a very good BC of about .192.

      However, current 5.56mm loads provide considerably better performance against unarmored targets at ranges below 500m, due to their bullet construction.

  • Hi, Patriot Gunner,

    I agree that your chances aren’t good if you get shot by – for example – Hornady .308 TAP firing a 110gr tipped hollow point at close to 3,000 ft/s in the center of mass, but actually wounds by traditional full-caliber FMJs (such as 7.62x54R ball) have proven pretty survivable. The problem is that these FMJs don’t tend to fragment much, and they upset later than the smaller caliber rounds.

    Certainly, these rounds are lethal and can be highly effective, but if you lined me up against a wall and gave me the choice of being shot with either a Romanian 8mm S Patrone or a US 5.56mm M193 ball round, while I was thinking of ways to escape, I would lean towards the 8mm.

    • Patriot Gunner

      Ha! Great reference to the 8mm S Patrone, you Sir are a brave man! I think you hit the nail on the head with FMJ/ball rounds and within those confines, yes the SCHV rounds do tumble/fragment and dump their energy quite efficiently. I just wish we didn’t have to work within the confines of the Geneva Convention, I know this is a firearms blog and politics is strictly verboten! But in this case, they are inseparable. Think of the possibilities if we could actually use expanding bullets in combat, I think that would quiet a lot of the 5.56 detractors. One can only hope.


      • I don’t feel that restrictions on bullet types – barring gas/poison/toxic etc. – are very effective at reducing pain and suffering, but I do think expanding bullets have major limitations in military use, specifically in penetration. So for some roles – such as a general issue round – they leave a bit to be desired in that area.

        • Patriot Gunner

          True, but it does greatly depend on the design of the bullet. We already have many designs of expanding bullets on the market that have shown to perform very well with soft body armor and other barriers, I don’t want to be a called a shill so I won’t name any specific companies. But if you are referring to hard barriers, then yes I would agree with you there, however, SCHV overall isn’t that great for hard barriers to begin with. Price would definitely be another factor as expanding bullets cost more to produce. Bottom line is that gun/ammo selection is just like anything else in life: a balance of pros/cons. Some designs have more pros and some more cons, but overall I think the AR-15/M16 5.56 combo does have more pros than cons. I think one would be quite well equipped with an AR-15 chambered in 5.56 when the inevitable hoard of zombies come.

          Nathaniel, looks like your article struck a chord (nerve maybe?) with the gun/TFB community, I don’t think I’ve ever seen an article with this many comments before on TFB. Might I suggest in your next article you do a comparison between an AK 74 vs AR-15? But pick a definitive winner…I’m sure it won’t draw any negative attention 😉

          • I wrote an article that got almost 600 comments before, so this one has a ways to go. 😉

      • Georgiaboy61

        Re: ” Think of the possibilities if we could actually use expanding bullets in combat, I think that would quiet a lot of the 5.56 detractors.”

        Actually, we already use “expanding bullets” in combat, at least after a fashion – namely, OTM (open-tip match) projectiles. OTMs, as produced by such high-end bullet makers as Hornady, Berger, Sierra, et. al. are usually formed in such a way that the gilding metal/copper jacket enclosing the core is drawn up – like petals on a flower, if you will – into a point at the tip of the bullet. Typically, the very tip is either left with a small metplat or topped with an aerodynamic point, like the kind used in Hornady’s A-Max line.

        I recall seeing someplace that OTMs, since they are not made, per se, as expanding projectiles, are considered legal under the rules of land warfare. According to these accounts, they open reliably at most combat ranges and at a wide range of muzzle velocities and function much like hollow-point/expanding projectiles in terms of their terminal ballistics.

        As effective as a purpose-designed expanding or HP bullet in inflicting tissue damage? Probably not, but OTMs are much more accurate than run-of-the-mill FMJs/mil-spec ball, and also have superior terminal ballistics as well – at least against targets in the open, not behind cover, not wearing body armor, etc.

        Precision military shooters have been using OTMs for years. And if it is good-enough for those guys…. well, you know the rest. Cheers…

        • OTMs of the familiar type (e.g., Sierra MatchKing, Lapua Scenar), do not expand, but perform similarly to FMJs with thin jackets (i.e., they fragment). The big difference is that the top of an OTM is not reinforced, so fragmentation is more likely than with an FMJ.

          This is not to say there are no OTMs that expand – the V-Max line could be considered one such type, but they are not JAG approved.

          • Georgiaboy61

            Nathaniel, all I have heard is that our special ops personnel have used OTM rounds in combat and that they have performed well. “If it is good enough for them,” etc. etc.

          • Fragmentation can be very devastating. 🙂

  • This is a new comment directed to Nathan F.

    First thank you for your work, I truly enjoy the technical aspects that you are bringing to the blog.

    I have been following the development of 6.8 from the start, and the initial description of 6.8 from “The Black Rifle II” by Bartocci is incorrect. The cartridge was not designed as a precision rifle cartridge with capabilities out to 450m. It was designed to maximize terminal effect from 0-300m from a shorter AR platform without too much compromise of accuracy, capacity, or long distance ballistics. I think you put too much stock into one unsupported line from Bartocci’s book. If you look to contemporaneous statements from those with knowledge of the development of 6.8, like for example Doc GK Roberts, the assertion is repeatedly made that the 6.8 is designed to primarily be a 0-300m cartridge, as it was addressing the “not enough stopping power” and “poor barrier performance” complaints about the M855. I agree in whole with your analysis of 6.8, and you should ask yourself, if 6.8 was designed as a precision cartridge out to 450m, how was this the result? Clearly an improved 5.56, 6.0, 6.5, or .25 would have been superior with distance and precision as design goals. Your own analysis indicates that the only way that 6.8 makes sense is if was designed as a closer in, more terminally effective, barrier penetrating upgrade over M855. Many smart engineers and end users had a hand in the development of 6.8, how would they have designed a round so unsuited for Bartocci”s described goal of 450m?
    One other point regarding Hornady’s new MK262. You state that it has a MAP of 68000psi. The sources that you link to do not support this number, and it is far above any NATO standard. Where did that number come from? If you used one of the modeling programs to derive that number, I think it needs to be revised, as I would guess that Hornady is using one of their complex base powders (similar to Superformance) to get a precisely tailored pressure curve.

    • Hello, Ando! Thank you for commenting.

      Chris Bartocci’s description is corroborated by Zak Smith’s 6.8 SPC history.

      You are the first commenter to hit on the key implication of this article, which is “why would anyone design a DMR cartridge like this?” I do not know the answer, but I think this rant by the round’s designer Cris Murray gives a little insight into his thinking.

      I have found Gary Roberts’ statements on the 6.8 SPC (and other subjects) to be inconsistent, both with his own previous claims and with better-supported statements made by others. Because of this, I typically do not put much stock in anything he says, unless it is verified by another trusted source.

      Hornady does not make a Mk. 262. I mention in the article that the latter 75gr Hornady BTHP load is simulating if you took a Mk. 262 round, pulled the bullet, inserted the Hornady T1 75gr BTHP, and re-crimped and sealed it exactly as it was. I do not reference Hornady performance figures anywhere in the article (not even their ballistic coefficient numbers).

      The pressure figures come from my own estimates – in the article I do say the MAP is “about” 68,000 PSI, which I believe to be true. It is certainly higher than M855A1 (approx. 63,000 PSI), as velocity figures for the Mk. 262 show it providing more energy with a heavier bullet of approximately the same length and bearing surface as the M855A1 while using similar propellant. This can only be achieved by raising the pressure level, and because of this I am confident in the 68,000 PSI figure. That pressure figure – you’ll note – is not used anywhere in the article to derive performance, it is only cited as an example.

  • Lasis

    I’m sorry, but doesn’t the inability to fragment actually mean US are following to international agreements in small arms ammo (no fragmenting, explosive and expansive military ammo)?

    • Fragmentation is not something the Hague Convention lists as prohibited.

      The water-in-the-bore problem has not been a major issue for 5.56mm and 5.45mm weapons worldwide in the past 50 years.

      • Lasis

        By itself water isn’t a problem, of course, but it is when coupled with dirt. Which shouldn’t be a big problem too, unless someone sticks a barrel in the mud. OK, OK, maybe I’m exaggerating this issue and it’s not an issue at all, besides, soldiers can always apply condoms before mud bath, just in case.

  • Fegelein

    So all the 6mm stuff that has been going on for darn near a century, experiments showing that a roughly .270in or 6.8mm cartridge with a case length between 30mm and 50mm ought to be roughly the optimized ideal medium game / combat rifle cartridge are wrong just because 5.56 generates a bit more pressure and flies slightly straighter at extreme ranges which are only ever tackled with proper full size rifle cartridges, anyway. Did you ever think about the complaints which led to the development of 6.8? Did you think at all about the practical side in terms of checking on the giving and receiving ends of the equation, whether in terms of field reports, barrier penetration, incapacitation speed, rounds per kill, rate of successful vs unsuccessful stops, wound ballistics, ammo weight, magazine capacity, reliability, controllability, felt recoil, muzzle rise, shot split times, muzzle flash, versatility, optimal barrel lengths, or impact on handling characteristics between the two calibers? No, of course you didn’t, because accounting for the difference between theory and reality would have ruined your argument. 6.8 is a round considered acceptable for taking deer, which are more or less human-sized, anywhere in the U.S., whereas 5.56 is prohibited against that role in a very large number of jurisdictions due to not being able to reliable achieve a humane kill. 6.8 Wound tracks are generally larger and nastier than 5.56 wound tracks according to the very well respected Dr. Fackler, and a quick search for compared penetration and wounding brings up results which corroborate this. I am deeply sorry that 6.8, despite not being as completely impressive on paper as 5.56, does perform significantly better than 5.56 when actually used on targets. Within personal weapons range, 5.56 and 6.8 have virtually identical arcs and drift. According to even your numbers, it is only when more extreme ranges, such as 600M+, which are normally reserved for sniper rifles and CSW’s, which fire full length 30 cal rounds, that the differences become significant, and they only become large at around 700M+. You numbers also illustrate the fact that 6.8 has significantly greater energy at personal small arms engagement ranges, as well as has a greater diameter means that the cartridge is doing exactly what was intended of it: Offer improved lethality and penetration at typical engagement distances, which, according to actual studied done, are almost as a rule within 300M, and often take place at even shorter ranges. Long range engagements are the domain of heavier weapon — not assault rifles, which were never designed for that kind of purpose and indeed lack the capability as getting that long range capability would have prevented them from being controllable and lightweight.

    • There are fewer examples citing .270 as the ideal caliber (I can think of only two offhand) than you think, and more citing .22 as the ideal caliber (three from the US alone).

      Good wound ballistics have been achieved with the 6.8 using projectiles like the Hornady V-Max. Using FMJ projectiles, it creates wounds like 7.62×39 FMJs. Even when using BTHPs, I have demonstrated that there are serious doubts about the 6.8mms consistency at ranges beyond 150-200m.

      All of your other objections I have addressed previously in this article.

      • Doge

        Wow. So reply. Very refute. Many defend. Much convince. Wow.

    • Krebs

      Good post, Fegel. This guy is talking out of his ass to tyr to deny that he’s saying what he’s saying. You make excellent points and more importantly don’t make every single thing you ever post be about some pet weapon or caliber. That alone makes you far more trustworthy than this clown.

  • CZfan

    Very cool article showing a bunch of different examples of what I have thought for a long time. The 6.8 SPC is a terrible “solution” to a problem that has been fixed with the mk262mod0 ammo, and the M855A1EPR.

    A few years ago I really considered building an alternate caliber AR-15, I would love to have an AR-10, Preferably the Larue OBR .308, but I dont have $3,000 dollars to drop, so I decided to look into AR-15 lower compatible rounds.

    After a lot of looking my choices were between .300 Blackout and 6.8 SPC.

    I did alot of ballistics “testing” on my Sierra I6 program and couldnt believe what I was seeing. I thought I was messing up somewhere when the 69, 75 and 77 gr 5.56 projectiles from Sierra, Berger, and Hornady all performed as well as the 6.8 out to 300-400 yds and then they had better velocity, less drop and more energy delivered to the target. Not to mention at all ranges the 69-77 gr 5.56 round bucked wind better than any of the 6.8’s.

    For all the hype that magazines and other firearm publications gave the 6.8 I couldnt believe how marginal the 6.8 was at everything especially when it was compared to a 77gr 5.56.
    The only thing you could say it has an advantage on is that a 115gr round “hits harder” than a 77gr. even though out to 300ys the 77 and 75 gr 5.56 rounds are neck and neck with the 6.8 when comparing energy, and past 300-400 yds the heavy 5.56 rounds deliver more energy on target.

    So I started looking closer at the .300 AAC because I was not going to spend the kind of money it would take to build and shoot a 6.8 SPC and get worse performance across the board than a 5.56. Its cheaper to buy match grade CBC, Black hills, or any other brand of 77gr .223 or 5.56 than it is to buy just standard 6.8 SPC.

    And again I came to the same conclusion that yes even though the .300 AAC is a very different round, running it subsonic with a suppressor out of an AR is very cool, and a 220 grain round or 150 grain round will certainly hit harder than a 77gr 5.56, the range is incredibly limited with the .300 AAC. Yes you can shoot it out to 500-600 yds but the amount of drop is almost double when comparing it to a 77gr .223.
    Again with the ammo cost I couldnt see the point to building a .300 AAC over a 5.56

    So I ended up getting a medium profile CHF spikes tactical barrel and built myself an “SPR” and stuck with 77 and 75 gr 5.56. Ive shot it out to 750 yds and even though the wind is a pain at that distance with a small bullet the alternatives are worse.

    If I were to pick a replacement for the 5.56 for the military, I would stick with the AR-15 platform and switch calibers to the 6.5 Grendel.

    I think the best AR-15 alternate caliber is the 6.5 Grendel, granted the magazines are expensive and limited capacity compared to the .223/5.56 but the short square charge pushes the 90-130gr 6.5 caliber rounds to speeds that are near equal to the velocity of the 55- 77gr 5.56.

    the 6.5 shooting a 130gr projectile at 2650 fps, not only hits hard at short range, the thing retains its velocity, energy and accuracy out to 1,000 yds. the 144gr Lapua FMJBT with a muzzle velocity of 2450fps out of a 24″ barrel will still be traveling at over 1200 fps at 1,000 yds.
    So take that round and put it in a 20″ barreled “M16” and you have supersonic velocity with a 123 gr round well out past 750yds.
    With shorter barrels like 14.5’s you will certainly have supersonic 6.5’s out past 500yds
    Granted the 6.5 is alot heavier than the 5.56, the size of the bullet gives you alot of wiggle room with its design.

    If someone came up with a 6.5 grendel copy of the m855A1 EPR bullet even at 100 gr, that thing would be a phenomenal combat round. 100gr rounds at over 3,000 fps with such a long bullet that no matter the velocity it will yaw and fragment in a target. and it will have the oomph to go through barriers. Especially with a good design like the EPR round.

    Simply mass produce a 77gr round and issue it to all the troops, keep the match grade ammo for the designated marksmen, all the barrels are 1-7 already, so they will shoot it. And if the EPR is as good as they say issue that too. Its supposedly very reliable at all velocities to yaw and fragment, and at optimal velocities they say it produces wounding like a 147gr ball .308.

    • After writing this article, I took a look at what 6.5 Grendel uppers are available, and it seems they can be quite reasonable in price.

      I have shot 5.56mm 62gr ammunition to 900 meters before; it’s possible, but clearly not ideal. 77gr ammunition helps a lot.

  • michel Baikrich

    Sorry I speak only French and Spanish, but with Google translator is not a problem

    Excelente estudio comparativo, pero lo importante es tambien la composicion del proyectil; en funcion del objectivo operacional… Porque una comparacion nunca sera completa sin hablar de los diferentes tipos de bullets y sus efectos


    Ballistic & weapons Eng. (Liege-Belgium)

    • Michel,

      Yes, I agree that there were many other projectile types I could have studied, however there are only so many words I can put into one article!

      Thank you for commenting, and feel free to email me at

  • Coolhand77

    That is why many of us, early on, considered the 6.5 Grendel a better option over the 6.8 SPC. Gave you the close range “energy” of the 6.8, but retained energy/velocity at longer ranges, even passing the 7.62×51 before going subsonic.

  • Misha

    All I got out of this article is that 5.56 is superior to 6.8 provided you torture the criteria hard enough to make it so that the most important thing for an intermediate SCHV carbine round fired from a weapon intended for close to medium range is how well it flies in the >700 meter range.

    • Virtually all of the criteria I identify, besides the Mach 1 threshold, exist below 600m.

  • Gary

    Great article but only about 2% of the military get to use the MK262 cartridge…Everyone else has to use the not so great M855 so your not comparing apples to apples…Now run the numbers on M855 vs 6.8 SPC and you will see a vast improvement…

    • M855A1 is standard issue. Further, it’s not as though the whole military would have gotten to use the 6.8, either, as it was intended to replace Mk. 262.

      Not unless it had been issued as an FMJ or something similar, which would have made it a very poor performer indeed.

  • Kivaari

    If anyone thinks they are coming up with a new wildcat cartridge don’t waste your time. Essentially you can take any existing cartridge case and someone in the last 110 years has done it already. You could find better performance through the use of new powders.
    Things like the ‘-06 case have been used with every bullet from .224 -.400. The 57mm Mauser case has had every diameter bullet stuffed into it. Like the 6mm Remington, it is Mausers 6x57mm. The 6.5mm Mannlicher case has had a similar treatment. Even the 7.62x39mm has been tried from .22 and up. The Soviets were developing a .22 (5.5mm) cartridge before WW2. The Swiss were doing the same. The Germans were late bloomers, but they brought their 7.92x33mm to fruition in significant numbers. Like the .223 Remington case, every bore size from .177 (4.5mm) to .30 (maybe more) has been tried. Find P.O. Ackley’s book from 50 years ago, and you will see your dreams from this morning represented in his book.
    We don’t need a new infantry rifle or caliber, at this time. Only finding a safe and reliable and durable caseless round will change things. Our M16 family of rifles is superior to almost every other design out there. Yes, I know some think it is unable to kill men. Every rifle in common use fails at times.
    If a larger bore diameter in the same package perform better than the 5.56mm I have yet to see it.

  • ftyjyry

    As long as it can take out a hog at 100 yards, I’m good with it.

  • Lee

    6.5 never caught on with civilians cause…

    1.most people dont shoot at a long enough range to appreciate a 6.5.

    2.for the longest time Alexander arms was the only quality manufacturer of 6.5 uppers. $$$
    Whereas everyone was making 6.8 rifles at a lower price point.

    3. The 6.8, although originally marketed as a military round, was re branded as the simple mans hunting cartridge. In texas, academy is stacked with readily available 6.8 caliber ammo. Your lucky to find any 6.5 ammo at a store…even today.

    • I didn’t compare the 6.8mm to the 6.5mm Grendel.

      • Lee

        Your correct. Anytime you talk about the 6.8 everyone jumps into a spc vs grendel debate and I wanted to explain that for the “civilian” market the 6.8 was just marketed better than the 6.5 grendel. I meant to reply to another poster but it commented up here. Excellent work man…I can tell alot or research went into this article.

  • lifetimearearesident

    I’m a simple guy. So I looked at the 6.8, considered the number of major AR manufacturers who offered the caliber and jumped in. Now I’m not like most of you sharpshooters who can hit a fly at a thousand yards. Most of my shots are inside 100 yards. For me it’s a great caliber for deer. From what I hear it’s pretty good on hogs too. Works for me just fine. But I still am proud of my 30-30 too. So go ahead and debate away. I will just go out and shoot what I have and be happy.

  • Kivaari

    None of this is new or leading edge technology. Does anyone remember the .276 Pederson? A pre-WW2 US Army developmental cartridge that would have made more sense than the continued use of the .30-06. A compact 7mm round, similar to the British .280 of EM2 fame.
    None of those were cutting edge either. The Soviets used a few thousand select-fire rifles in 6.5mm Japanese, during the post revolution Russian Civil War. Almost all of those cartridges used the older 6.5mm Mannlicher cases, like the 7.62x39mm M43 case.
    We have an advantage today because of superior bullets and more efficient powders. We continue trying to invent a new platform and cartridge, while our grand fathers and fathers tried these designs nearly 100 years ago to now. No one is inventing anything new.

  • Uniform223

    Great read!!!

  • Jimbo

    I’m amazed that someone would analyze the round to this degree. I guess i’m lazy. Shoot it and see seems a lot more fun.

  • Kivaari

    Ok, here’s more to add to the mix. We did have a rifle and cartridge that could be a starting point. Earlier I said we have seen and had cartridges that came and went. The US Navy adopted the 6x60mm (.236) cartridge in 1895. The basic case is very similar to the 6.5mm M-S. The rim diameter is essentially the same as the AKs 7.62x39mm. We have tried “advanced designs” in the past. We can see where the rifle failed because of design defects. The cartridge failed because it did not have adequate powders. What many are asking for is something like this case with a 6mm-7mm bore. All this needs is a shorter neck, a good bullet using good powder, all in a new rifle. Our military has been there and done that many times over the last 125 years. Or take the 6.5mm Japanese cartridge, add a good bullet and better powder and we have one more new combination.

    • I have been studying these sorts of rounds for years, and I remain unconvinced about the concept. I think SCHV still has a lot of merit that remains unaccounted for in most analyses.

      • Kivaari

        The SCHV in reality are not so High Velocity. Like our M855, it isn’t all that different from the 7.62mm NATO. I used pretty much all of the military rounds from 1890 to present. I have not used the 5.45mm or 6.8mm. I find the 5.56mm to be a better choice than almost all the others. “The MIX” of performance, bulk, weight, trajectory and weapons of reasonable size and weight is the best – for me. I still hold the opinion that it is all our military needs for general issue, and all we need to do to make it better, is training. We just don’t train soldiers enough. Marines have the tradition of making riflemen out of men (ok, women as well). I don’t know how they train riflemen today, but in my era marines could shoot well. Do that and we win battles. Add good optics and we win the battles faster with fewer casualties on our side.

        • M855 is still running 890 m/s velocity from a 14.5″ barrel. That’s a lot higher than M80 from a comparable barrel length.

          • Kivaari

            Yep! Most 7.62mm NATO rifles use 17-20″ tubes. It is a mistake to shorten them to get a rifle the size of an M4. If I had the power to influence rifle purchases, I’d have picked a 16″ mid-length M4-type carbine. That 1.5 inch difference isn’t much, but I like it. All the chopped 7.62mm NATO caliber rifles have excessive muzzle flashes, which is a negative thing in all settings outside of Burbank movie studios. I have used quite a few battle rifles. The M14 and FAL are good machines. I just found it hard to carry lots of ammo and rations. They do perform, and if your unit has a good logistics chain that isn’t a big deal. It does demand restraining the trigger finger from sending too many rounds down range. I found the HK91 to be a handy sized rifle, but of the three I had, I could never get them to shoot much better than an AK. 3.5-5″ groups were the norm with or without a scope. I had SKS carbines that would hold tighter groups.
            I think the military has done a much better job of finding good accessories to enhance the performance of the M16 platform.
            The Marines have really improved the performance of its fighters with the addition of a good optic, Give a Marine trained with iron sights, an ACOG, and they kill the enemy more efficiently.

  • michel Baikrich

    Gracias Nathaniel por sus comentarios

    En este momento estoy trabajando sobre una nueva gama de municiones para reemplazar a la venerable 9mm Luger, con mas range y capacidad de penetrar 48 layers de kevlar de 1000 d + 3mm steel a 150m distance, con un barrel de 150mm (6″)

    Igualmente trabajo sobre los kits de conversion para cualquier armas en calibre 9mm

    A este efecto, busco un partner industrial serio y solido para reproducir y comercializar estas municiones con los cañons de conversion

    In first discussion under NDA



  • LilWolfy

    The funny thing is that one of the Army Ordnance engineers approached McNamara’s Whiz Kids and suggested what is being discussed here for a military cartridge to meet the SCHV concept, knowing that the .222 Remington Special case and AR15 was being pushed much too hard to meet the 3400fps goal. This was after the Pentagon, USAF, and SECDEF became involved after complaints that Army Ordnance Board had been sabotaging the AR15 against the M14, in order to doctor the outcome in favor of the M14 (which failed even with their tampering).

    He suggested a cartridge based off of the .25 Remington, necked down to .224″, because the SCHV proponents had held strongly to the .224″ caliber. This would have required a re-design of the AR15 around FOS for an increased case diameter, and it was suspected to be another Ordnance Board attempt to bog down the AR15 with a re-design, which would kill momentum of the program.

    That cartridge would look basically like a 5.56×43 6.8 Wildcat, in a slightly-enlarged AR15, pushing a 68gr FMJBT at 3400fps at lower pressures in the 55ksi region.

  • Kivaari

    What people seem to miss is that any rifle caliber suitable for military or hunting, can kill any living thing on the planet.

  • Kenneth Chaffins

    More than a bit late to the table it seems..that happens from time to time. As a owner of a six eight, I seriously have to question all of your graphs. First..seriously? You’re comparing a 77 grain cartridge to a 115, and 110 grain? At those weights, of course you’re gonna get 2450fps to 2600fps from the 6.8. And while you might have used a Spec II chamber for the 6.8, you used the original SAAMI loadings for the round, the out of date loadings. Before Hornady bought them out, Silver State Armory released ammo for the 6.8 in Spec II loadings, 75 grain projectiles burning at 3200fps, 90 grain projectiles burning at 3100fps, 100 grain projectiles burning in at 2750fps, and they do exactly what SOCCOM designed the round for: It delivers flatter trajectory out to range, hits harder than 5.56, AND 7.62x39mm, No, they aren’t the largest, heaviest rounds available for the caliber, but even when using Spec II loadings, the largest rounds still aren’t outclassed by the 5.56. I’ve owned one of these rifles for four years now, and yes, there are better calibers out there, but if you’re gonna do a comparison, make sure it’s more accurate than this hodgepodge you’ve photoshopped together, just to defend the caliber of your choice.

    • 1. I compared the projectile weights for which the 6.8 SPC was originally designed, as the article concerns the role for which the round was originally designed.

      2. I did not use figures from a Spec II chamber. The figures I used were not taken from any specific source, but reference performance figures obtained with SSA ammunition from an AR Performance DMR chamber.

      3. I did not use the original SAAMI loadings. I used SSA loadings as a reference for the figures used. The pressure of those rounds was at the maximum allowable limit for SAAMI spec ammunition from the DMR chamber and therefore is not representative of SAAMI spec ammunition from an SPC chamber.

      4. Yet more unsourced performance numbers. Even ATK advertising material cites their 90gr GD ammunition as having a muzzle velocity of 2,900 ft/s from a 16″ barrel. What is worrisome about these performance figures being bandied about is that the 6.8 SPC – like other rounds – is constrained by physics. Given that the thermodynamic efficiencies of modern small arms are highly comparable to one another, and given that only modest gains in piezometric efficiency are possible, the citation of figures such as yours, which claim energy levels 15%+ higher even than ammunition made by 6.8mm-specialist manufacturers (such as SSA) fired through SPC II and DMR chambers, imply the creation of some very, very dangerous high pressure handloads within the 6.8 hobbyist community.

      In short, the 6.8mm is a cartridge just like any other, and it is not capable of arbitrarily high energy levels within safe pressures. It is very concerning indeed to see a round that is decidedly in the same class as 7.62×39 or 6.5 Grendel quoted as having energy levels 30% higher.

      5. SOCOM did not design the round. Cris Murray the AMU and MSG Steve Holland of 5th SFG did.

      6. It clearly does not provide flatter trajectory out to range. How can it, when it is crippled by low-BC bullets and low muzzle velocity?

      7. I did not use Photoshop in making this article. I used Microsoft Excel.

      8. Here is a comparison between lightweight 6.8 SPC loadings and M193. The SPC is… Disappointing.

  • The Brigadier

    Very good article. Another important consideration is how much force is applied by both bullets upon impact. That can be measured simply from data in Nate’s first table and using Newton’s grand physics equation F=MA where F is force, M is mass and A is acceleration. For bullet cartridges or shells of any size including massive field artillery, this equation can tell us how much force can be applied to a target by a non-exploding projectile,

    For M mass, simply substitute the bullet weight in grains. For A acceleration use the published muzzle velocity, For the mouse bullet a mass of 55 grains times 2678 muzzle velocity gives us an impact Force of 147,290. For the deer bullet, a mass of 77 grains times 2490 muzzle velocity gives a Force of 191,730. Clearly the .268 will strike a target with more force than the .556 regardless of its other faults.

    We used to have fun with Newton’s equation in the eternal dispute over the merits of light and fast rounds versus those that are heavy and slow. Like a .357 magnum with 125 grain bullets at 1540 ft/sec versus a .45 M1A1 with 230 grain bullets at 850 ft/sec. The results of any two calibers can be quickly calculated and compared for an impact force calculation thanks to Sir Isaac.

    • First, thank you for the kind words. 🙂

      What you’ve calculated is the momentum of the round. I explain why momentum is not relevant for forming an overall picture of “stopping power” against organic targets here.


      • The Brigadier

        ‘Fraid not Nate. The F in the equation is clearly Force. Force can be measured by a ball that is hit by a baseball bat. Several different force calculations there. It can be measured as blunt force or precise force. While damage to organic targets can be affected by bullet shape, the impact shock from the force can be clearly measured. I know this equation is not fully understood, but it clearly shows the difference in applied force for various powder loads and various bullet weights. I like your articles, but your defense of .223 is bordering on mania as your claim that equation is only about momentum.

        I’m a .308 guy, but I qualified as a marksman with a M16 A1. The .223 AR family of rifles is one of the most accurate group of long arms in the world. Its called the “mouse” or the “Barbie rifle” for a reason. I saw guys hit by .556mm all over the world. Some were hit and died instantly. Others had to be shot four or five times before they dropped. Usually one shot by a .308 was sufficient to rid the world of the person shot. Greater bullet weight and a little less speed than a .223 results in a much greater applied force with predictable results for the .308.

        One more thing. H&K stated a couple of years back that they came up with a lower receiver for ARs that absolutely fixes the jamming problem. If that is true and they can make the thing for a lot less than the $700 plus price tag they want, then AR10s for .308 will become a reality with all the increased power and none of the drawbacks of Stoner’s design. How about an article about this breakthrough and maybe we can all celebrate? A lot less recoil and a lot more applied force. By the way 168 grain bullets are the perfect weight for .308 rifles in terms of accuracy and these ruled Camp Perry until the Barbie rifles were allowed to compete and won it ever since.

        • Hi Brigadier.

          Force is mass times acceleration, and acceleration is measured in units of distance per second squared. If you are multiplying mass by a unit of distance per second, then you are calculating momentum.


        • Wes

          Brig, Nate doesn’t listen to end users. To sum up his three responses (when he does respond)

          A: Gets a bleat from a sheep. Thanks them for agreeing with him.
          B: Gets told by another theorist that he’s wrong or his conclusions are insane. Tells them they’re wrong / accuses them of trying to troll or steal his job / claims that his claims and data are not what they are / claims that the people who contradict him actually support him.
          C: Gets told by an end user that they disagree with his conclusions. Condescendingly agrees parts of their response which don’t challenge him while quietly hoping that nobody notices that he didn’t at try to refute someone with real world knowledge contradicting his theoretical postulates.

  • It can fail to fragment, but that does not mean it cannot fragment. This is all academic, anyway, as M855 is on its way out.

  • LilWolfy

    Jordan and Saudi Arabia’s purchases are typical of Middle Eastern Sunni or Heshemite Kingdoms where their procurement practices are very susceptible to a salesman who knows how to hype up his product.

    The USMC has achieved as good terminal ballistics with the Mk.318 SOST, while US Army SF has done so with the 70gr Barnes TSX 5.56 load, which folds dudes over even from 10.5″ guns.

  • dittybopper

    I’ve got a couple of questions:

    1. Why set the external ballistics calculations all the way out to 1,000 meters? *NOBODY* expects either round to be used at that distance. A better comparison would be to set the range to 500 meters, or perhaps even a bit shorter, maybe 300 meters. This is like comparing the performance of standard velocity 40 grain .22 LR with 32 grain CCI Stingers at 200 yards. Interesting, perhaps, but ultimately useless as a source of comparison, as they are normally used at less than half that range.

    Those drop and drift charts are essentially useless for comparing the two rounds to each other at sane engagement ranges for those calibers.

    2. Why is the faster .223 round “unexpectedly” better at resisting wind drift? At a 90 degree wind angle the only thing important to wind drift is the time to target, and that is solely dependent on velocity, not mass. The bullet that gets to the target faster is going to suffer less drift, even if it is significantly lighter than the slower bullet.

    I don’t own a firearm in either caliber, and I mainly shoot flintlocks, so I don’t actually have a dog in this fight, but I’ve been doing ballistics comparisons for about 25 years now, and those two things just stood out to me as wrong.

    • Smit

      Hush or you’ll make everybody realize that the emperor has no clothes.

    • Tassiebush

      The point of the extreme range calculations rather than the classic 300m mark is because extreme range matters. Especially in recent usage.

  • Reading thru the article I kept wondering why they didn’t go the short magnum route? Sure you might need to use special mags and have them single stacked, but if the desired result was longer range and energy in a short cartridge, hasn’t that already been done by the WSM loadings?