The US Army Marksmanship Unit’s .264 USA

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Header image: The .264 USA on a display block, flanked by 7.62x51mm (left) and 5.56x45mm NATO (right). Modeled and rendered by the author in SolidWorks. The .264 USA was designed by members of the Army Marksmanship Unit as a possible next-generation military rifle cartridge.

It’s been an interesting decade for military cartridge development. It’s reasonable to guess that at no other time in this country’s history have there been so many home-grown proposals for military rifle and machine gun ammunition as in the ten plus years following the invasion of Iraq. Even though my own opinions on the subject are pretty conservative, it’s great to see so much discussion and attention paid to the subject of my interest.

One of the schools of thought that has gained some ground within the Army itself is the idea of a “general purpose round”, a proposal to replace the current two-caliber system of 5.56mm and 7.62mm ammunition with a single round, usually somewhere in-between those two calibers in size and weight.

It’s a theory I am highly critical of, but that does not mean it is without merit. The paradigm has definite benefits, and should be investigated even if there is some certainty that, at the moment, it’s not practical or desirable to implement such a scheme. So it’s right that the Army Marksmanship Unit has endeavored to produce and test a round that could fulfill such a role, called the .264 USA. The round is a 6.5mm caliber round, based on lengthened 7.62×39 brass, with very little case taper (0.26 degrees, almost half that of 5.56’s 0.5 degrees, and still considerably less than 7.62x51mm’s 0.35 degrees) but a very slender 17.5 degree shoulder. At 2.6″ long, the .264 USA is closer to 7.62mm than 5.56mm in size and weight, but it nonetheless would afford slightly smaller and lighter weapons and magazines. Interestingly, due to a request for proposal specifying a certain number of conventional-layout polymer cased rounds in this caliber be produced, there has been some speculation that the .264 USA’s unusual case taper and shoulder angle are indicative that it was designed from the outset for polymer cartridge cases. If this proves true, it would make the .264 USA the first caliber to my knowledge to be purpose designed for conventional layout polymer cases.

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Case dimensions for the .264 USA. Image source: iaaforum.org

The RFP linked above specifies that the .264 USA be capable of producing 2,875 ft/s with a 107gr lead-cored Sierra HPBT from a 16.7″ barrel, or 2,657 ft/s with a 123gr Sierra from the same length. Also mentioned is a .277 USA, producing 2,527 ft/s with a 135 gr Sierra, but much less is known about this cartridge. This level of performance is common to many different general purpose cartridge proposals, including that of Anthony G. Williams, so it appears the AMU is following suit with the .264 USA. The cartridge itself is very similar in size and weight to the design created for my evaluation in “The Case Against…” linked above, which confirms my suspicions about the considerable weight penalty of the GPC concept in general.

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This render by the author of the .264 USA, 7.62mm, and 5.56mm, shows the relative size of the three cartridges. The .264 USA, while undoubtedly more capable than the 5.56x45mm, is also much closer in size and weight to the 7.62x51mm NATO.

 

The .264 USA follows the 7x46mm UIAC, designed by Cris Murray (who was once also of the USAMU), very closely in performance. Further, it will be very close to the 7x46mm in size and weight, and therefore closer to 7.62mm in both respects than to 5.56mm. Because of this, while the .264 USA will afford somewhat lighter and more manageable weapons and ammunition than might be possible with the 7.62x51mm alone, it will negatively impact these characteristics relative to 5.56mm weapons. Whether this is deemed acceptable given the augmented ballistics remains to be seen.



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 can be reached via email at nathaniel.f@staff.thefirearmblog.com.


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  • Joe Smith

    This ought to be entertaining…..if anyone could screw up a .264 load, it’ll be the Army…..stay tuned.

    • Uniform223

      no, they screw up camouflage improvement programs.

      • Anonymoose

        >considering the M4(A1) to not be a horrendous screw-up
        >not just putting the collapsible stock on a full-length M16 for general issue (spec ops and support troops *might* be better off with the 14.5″, or a mid-length 16″)
        >not dropping the M240L program and replacing all the M60s and M240s (besides the C, D, and H versions) with the Mk48mod1, when all reports and tests said the Mk48 was better than the 240B or 240L, and cheaper than the L
        >M14s, M24s, and M110s still in service when the Mk17/Mk20 is available
        >ECH plagued with QC problems
        >Colt and Remington M4s plagued with QC problems
        >M9 with 15-round mags, in the desert
        >drooling over the .40S&W at the beginning of the MHS program and several past pistol programs, instead of the .357SIG
        >issuing 124gr 9mm instead of (+P) 147gr
        >Bradleys
        >Strykers
        >Humvees
        The list goes on and on and on.

        • Well, I can’t say I agree with very many of those. *shrug*

          • Anonymoose

            *shrugs back*

          • Skinnypete

            Ok spin doctor

          • Skinnypete

            198,600 spins per mins

          • Aw man, they removed the “196,800 spins per min” comment. I liked that one!

        • LilWolfy

          Not one of your complaints on small arms are valid. Let’s go through them:

          * M4(A1) was a heavensend
          * All reports on the Mk.48 from guys who actually know what they are doing indicate that it has serious problems overcoming trying to fit a cartridge it was never meant for
          * Mk17/20 is a total abortion, especially when you look at gas port location, and what the system does to critical items like TWS.
          * Colt M4’s plagued with QC problems? According to what HK article?
          * M9 is a boondoggle, but not critical
          * .357 Sig is a non-starter
          * Nothing wrong with 9mm ammo, it’s a handgun caliber

          • Commonsense23

            While I applaud you for rightly calling the MK20 a abortion, the 17 has made strides, still overall not a great gun though. But the MK48 doesn’t have any problems for what it was really designed for, stripping as much weight as possible for a primarily shoulder fired light machine gun. People get problems when they try to use it as GPMG thinking it can last as long as a 240 can.

        • Skinnypete73

          Do you just make stuff up to sound like you think you know what you think you thought? Yes my comment is as confusing as most of your ramblings.

        • MNOR

          Well the FN MINIMI was actually designed for 7.62×51 NATO when it first came around in the 80’s. It was the US. army who wanted it in 5.56. So FN did just that, and the US millitary got the M249 SAW.
          So, claiming that the mk48 was never intended for use with the 7.62x51mm.argument is pretty slim.

          In fact. Several NATO-memberstates are looking in to buying the newest 7.62 MINIMI-variant; The FN MAXIMI, trough exsisting FN-contracts they have with the 5.56 version.

      • Kivaari

        That ARPAT stuff was horrible. How they could screw that up is amazing. It would have been easier to work with the BDU Night camo, than “improve” what they had.

  • echelon

    I love the 6.5 Grendel and I think the .264 caliber has a lot of positives that outweigh the potential negatives.

    I’m not going to get into the whole general purpose vs. specialized debate, although I”m sure that will indeed be discussed.

    This is something I’ll continue to watch though I won’t get any hopes up of the military ever changing any time soon. That probably won’t happen until we develop weapons that magnetically fire super heated nano material rounds with delayed HO ability…

    • Well said, echelon.

      • LilWolfy

        The program goals of the LSAT are game-changing if they are successful, and I can tell you that from the end-user perspective when it comes to soldier’s load, particularly for SAW gunners and M240 gunners. If they develop a 6.5mm LSAT with a 130gr, bye-bye 7.62 NATO belt-fed.

        The weight reduction we’re looking at with that program’s success, as well as the space reduction with increased capability would be an overmatch for the 7.62x54R PKM machinegun, which is employed as an LMG due to its 17lb weight.

    • Jay

      Maybe there’s more to this than just playing around with a new cartridge. We all know LSAT is making progress and they already work on the 7.62 version.
      Maybe this new rounds, .264 USA and .277 USA, are made just to find the best intermediate load for the project.
      All this talk about traditional cartridge weight and logistics is futile when we think LSAT.
      When they switch to LSAT all this stuff already made for the 5.56 and 7.62 cartridges becomes obsolete anyway. The weight difference between calibers, with the LSAT architecture may be small enough to make the unified cartridge a lot more attractive.

      • echelon

        I think they just like to spend other peoples’ money…but what do I know. 😉

  • Camilo Emiliano Rosas Echeverr

    A 6.something intermediate round. What a novel idea.

  • iowaclass

    Jumps out to me as a good option. The logistical gain looks well worth any tactical trade-off that might be anticipated.

    • You’ve got to remember that 5.56 and 7.62 are already established. So, at least until a change-over can be made, there will be three rounds in service if the .264 USA is adopted in some form.

      Given that I think it’s unlikely that .264 USA can replace 5.56mm, there may always be legacy 5.56mm weapons around, even if 7.62mm is successfully phased out, which means there’s no real logistical streamlining to the idea.

      The cartridge would have to be much smaller to replace 5.56mm, and it doesn’t seem like many designers are willing to go that far.

  • ColaBox

    Im willing to bet this will just be another obscure boutique round that will never see the light of day just like 6.5 Grendel, 6.5 Creedmoor, 6.8SPC, .300BLK and so on.

    • Spidouz

      To me, for that purpose, the .25-45 Sharps looks pretty good on paper. For every other application, I think we already have what we need… with the .300BLK for a good round for suppressed ammo and the 6.5 Grendel for a good mid to long range precision… on top of the standard .223 and .308

      Personally, I’m more interested in some .223 Short (pretty much like the .22TCM), to have a more common cartridge in .22 caliber for both PDW/SBR rifle and pistol… technically what the 5.7 is supposed to be, but using regular .223 trimmed case with regular widely available and cheap .224 bullets.

      I’m more interested in the CQB to Short/Mid range…

      • 5.7×28 uses .224″ bullets.

        • Anonymoose

          We should give the .22 Spitfire another try, and NOT in an M1 Carbine this time.

          • .221 Fireball?

          • Kivaari

            It is “cute”. It would be easy to refine the original carbine into a modern weapon.

        • Spidouz

          I know that, thanks! But that’s about it…

          • Oh, excuse me. It sounded like you were saying it didn’t.

          • Spidouz

            No big deal Nathaniel.

            What I was saying is that I’m more interested in a .223 caliber that could be short enough to be used in both rifle and pistol, like the 5.7x28mm is, but using regular .223 cases, and more widely available and cheap bullet… generally already used in .223 such 50, 52, 55 or 62 gr… not some 23, 28 or 30 gr, less common and therefor more expensive.

            To me, for a caliber to become “popular”, it’s not only a matter of size and performance. It’s also a matter of already existing components such action, magazine, cases, bullets… mainly for people that want to reload, without too much extra steps with some coating and such like we can see with the 5.7X28mm.

            And that’s apparently what the .22TCM or the .223 Short try to accomplish from what I observed so far… but I’m still waiting to know more about it. But in reality, just collect some .223 cases at the range, trim them, and use your regular .224 bullet to reload your new cartridge you could use in both your semi-auto rifle or pistol… I like that. Ideally, it would convince better to try this new caliber.

            If I need to change everything I already have, from magazine, to action, dies, cases, bullets, etc… I might not be really motivated to try this new caliber, regardless how good it’s good on paper… mainly because there’s already so much good ones to be perfectly happy with (.308, .223, 6.5 Grendel, 6.5x47Lapua, .300BLK, well, you name it) and so much on the list to come in this 5 to 7mm range.

            That’s my point I guess. Sorry for the long reply, I just wanted to make my comment more clear than the previous one 😉

            PS: Please note that I’m not expert on ballistics. I do reload, but I’m _not_ a cartridge designer and I don’t have all knowledge on why one cartridge could be so much better than the other one. I only see it from my personal use, the result I could get from and the price I would pay for. That’s it!

            And I also don’t pay attention about the potential polymer case, because I don’t believe we’re gonna reload a polymer case if it ever happen… I doubt it. Therefor, I’m not quite interested… unless the price comes down very very low… but it’s typically not the case that is the most expensive part in a cartridge.

            My 2 cents 🙂

          • Kivaari

            At least for me the 5.7x28mm FiveseveN is a very awkward pistol. I hate the long reach to the trigger and that silly flip lever safety. If it is for general issue, I believe any pistol as odd sized as the 5.7 is wrong.

    • Commonsense23

      You know the .300 blackout is in heavy use with the SMUs right.

    • LilWolfy

      If your idea of never seeing the light of day is the above mentioned cartridges, then maybe you’ve been living under the proverbial rock in terms of what has been going on with cartridge development and mass distribution.

      All 4 of those cartridges are SAAMI rated, and there are over 30 factory loads for 6.5 Grendel, ranging from economy steel cased ammo, to premium hunting and target loads.

      6.5 Creedmoor is a fully supported cartridge by Hornady, the 30 TC necked down, and is very popular among target shooters and hunters.

      6.8 SPC has all kinds of factory loads for it.

      There is a continually expanding wave of larger calibers for the AR15, and more efficient ones for the AR10 that the civilian and military have been paying close attention to.

    • Kivaari

      Unlike the other rounds you mention, I actually found two .300 Blk at the range. Someone is shooting it.

  • Jack Morris

    I would love to see a load such as this standardized. The only reason I stay away from intermediate cartridges at the moment is availability, pricing, and weapon compatibility. I would buy an AR chambered for an intermediate caliber in a heartbeat if I knew the ammo and weapon parts would be as plentiful as the 5.56 style components.

    • woodman

      Learn to load your own ammo. Problem solved

      • Jack Morris

        I do load my own ammo. I just prefer to stick with mainstream cartridges. Much easier to snag components 🙂

      • Kivaari

        Chasing brass is tiresome. Over 35 years ago I was chasing Lapua 7.62x39mm with Berdan primers. It is a challenge to find it, pry the primer out, find 5.5mm Norma primers. I’d like to try a 6.8mm SPR, but all the negatives you want to avoid are unavoidable now. For me and my pension check to work what a 6.8 needs, is to cost the same as 5.56mm.
        Has there really been a problem getting ammo to the battle? I really don’t know. It just strikes me that the 5.56mm is doing ok with Blackhills heavy loads. I think a 16 or 18 inch barrel would get all the improvements needed.
        I like the mid-length carbines (16″). Maybe our problems have already been solved.

  • Joshua

    Will be interesting to see where this goes, but I doubt it will replace 5.56.

    • I agree. I don’t see how it could, given that it’s barely smaller than 7.62mm.

      • Cornelius Carroll

        I’m curious to hear about your thoughts on this idea: migrate primary weapons to something like an AR in an intermediate caliber and migrate secondary weapons to something like 4.6×30 and have said secondary weapons be more like a PDW and less like a pistol.

        • I don’t think you’d be doing the rifleman any favors, and I don’t see the benefit of commonality between linked and unlinked ammo.

          I think, though the 7.62mm is flawed, what we have now is pretty good. The only thing I might change is to give the platoon more flexibility to issue M240s or M60s in place of M249s if they’re being deployed to somewhere like Afghanistan. And, of course, it’d be best if there were something in the West like the PK, that was very light, reliable, and firing full-power ammunition.

          • LilWolfy

            What if you could have an LMG that is lighter than the SAW by half, with more retained energy than the PKM at 500m and farther, with a cartridge that fits within SAW nutsacks (ammo bags)…

            …and also uses an operating principle that basically eliminates muzzle climb and perceived recoil on auto?

          • That sounds like wishful thinking.

          • LilWolfy

            Ever heard of the Stoner LMG project? Maybe the Ultimax-100?

            Done and done for weight and recoil. Combine those types of designs with linked 6.5mm, game over. Game changer. Take an 11lb LMG that you can clear rooms with, then step out of the house for blocking positions, with an effective range of over 1250yds for supersonic reach at sea level.

            With the 130gr 6.5mm from a 20″ barrel, you exceed the PKM and M240 for retained energy by 300yds.

            I’ve been turning the gears on the ideal LMG for decades now, and all the components are there. We should be thinking overmatch to the PKM, with the proven Stoner LMG designs from the 1960’s-1980’s.

          • Here’s a picture of me firing an Ultimax 100:

            The 6.5 Grendel goes subsonic at about 700 meters, which is about the same as 5.56 and 7.62.

            I’m glad you’re enthusiastic about the cartridge, but it’s really just a 7.62×39 with better bullet selection.

          • LilWolfy

            So you’re familiar with the Ultimax-100 and constant recoil. Jim Sullivan was heavily influenced by Stoner’s work on LMG’s.

            I don’t know what load you are referencing for the 6.5 Grendel going subsonic at 700m, but it certainly isn’t one of the ones I’m talking about. Maybe a 100gr with a .359 BC, but definitely not anything 123gr or higher, even from a 14.5″ AR with the constraints of the AR15 barrel tenon.

            A purpose-built LMG and SASS family would enjoy slightly increased COL, and seat the 130gr with the boat tail junction at the neck and shoulder in the case. Larger barrel tenon nominal minimum and larger bolts allows full potential of the case’s pressure containment, but modern propellants can still keep it down away from 5.56 or 7.62 NATO pressures for weapon life and controllable cyclic rate.

            One of the biggest problems with the SAW, like the AK, is longevity. Those guns just don’t hold together well at all. Their crude operating system is the culprit, even with excessive weight for the SAW. It’s literally 2x as heavy as it needs to be.

            I certainly don’t see the benefits of a universal cartridge though for the US at least. The .264 USA is the last thing I would want RTO’s, FO’s, Combat Medics, PSG’s, PL’s, 1SG’s, CO’s, XO’s, AB’s, AG’s, and even riflemen carrying, since soldier’s load will be reduced, recoil increases, and there is no training to support the enhanced capabilities.

            It makes total sense for DM’s, Snipers, and LMG’s that would be capable of replacing the current medium MG’s, but I wonder if this is a proof of concept platform just to get a baseline with existing metallic cartridges, as well as a back-up in case LSAT proves longer in fielding.

          • Those claims about the 6.5 Grendel don’t make sense. It’s a well designed cartridge, yes, but to do what you claim it would have to have a thermal efficiency far above what a metallic cartridge shot through a steel barrel is capable of… Either that, or unsafe pressure levels.

      • DIR911911 .

        several comments seem to say this but do the math it is almost squarely in between the two calibers even a hair closer to the 5.56. the weight of the round is just a bit closer to the 7.62 but a little experiments with bullet weights and I’m sure you could come up with a bullet coming in at around 80grns going 3000fps which would be truly interesting to see since the 5.56 was originally designed to go that fast but all the shorter barrels won’t let it. maybe even making it a 6.0 or 6.2 would prove even better. if I could only come up with a few million for testing, haha 🙂

        • At 19.2 grams according to my estimates, it would be 60% heavier than 5.56mm. 7.62 is 24.2 grams in weight, which is just 26% heavier than the .264 USA with a 123gr bullet.

          In terms of energy, it’s 64% more energetic than 5.56mm, while 7.62mm is only 18% more energetic than it.

          For recoil, it has 67% more impulse than 5.56mm, while 7.62mm has only 21% more impulse than the .264.

          I’m not sure what your definition of “almost squarely in between the two calibers” is, but this does not fit mine. It’s clearly much closer in size, weight, and recoil to 7.62mm.

        • Kivaari

          Wouldn’t the reduction of bullet weight give up the advantages of having a longer LOW DRAG BULLET? I always thought the advantage of the 6.5mm bore diameter directly related to getting long range improvements. I could be quite wrong. The 5.56mm performs better when bullets are over 70 gr., better at holding all the nice things long range shooter like.

        • Kivaari

          If I remember correctly, the Finns adopted and adapted the Soviet 7.62x54mmR machinegun round to all the Finn rifles. The so-called “D” long range load. Finland had captured huge stock piles of it and after using it, found it was superior. Slower but holding onto the advantages of the spritzer-boat tail bullet over the flat based rifle round. All my Finn rifles were stamped with a “D”.

      • carcano

        How about the LSAT version of this cartridge?

        • Getting the weight down is good, of course, but lately I’ve been more worried about the recoil, TBH.

  • Evil13RT

    With the amount of equipment and experience already invested in 5.56, the gains need to be night and day to make up for the logistical trainwreck it’s going to unleash.

    • schizuki

      I’m not sure the transition from .30-06 to 7.62mmx51 was night and day, but they did it. Then added 5.56mm ten years later.

      • The late forties and early fifties were something of a dark, dark time for the US Army.

    • Court Spotts

      They are night and day….

    • jay

      If they decide to go LSAT telescoping plastic case, they’ll have to change all that equipment made for the two legacy cartridges anyway.
      May as well start fresh and go forward with a single intermediate cartridge, instead of having to start from scratch with two lines of products, one in 5.56mm and one in 7.62mm.

      • I see the appeal, but I’m not sure that’s practical, especially with LSAT.

  • Darrell

    6.5×55 FTW. 😀

  • RickH

    Unless science fiction becomes fact, one caliber to replace all will never happen….. in our lifetime. It’s kinda like having one fighter aircraft to fill all roles.

  • ClintTorres

    I’d like to see a shallower shoulder for more case capacity. This cartridge is just beggin’ for a 31-degree “improved” version.

    • That sounds excessive.

      • ClintTorres

        Yeah, you’re absolutely right! I’m all confused…I meant something like 90-30=60 degrees. Anyways more case capacity.

        • G

          There is already such a cartridge. It’s called 6.5×47 Lapua..

          They probably chose a 35 degree shoulder angle because works better with automatic weapons.

          • Different case head.

          • G

            Yes, I know. 6.5×47 uses a standard 308W bolt face.

            264 USA

          • G

            264 USA might make sense for the military. But IMO an improved version of 264 USA doesn’t make sense (even for civilians). If you want an improved version of 264 USA you could as well choose 6.5 Creedmoor or 6.5×47 Lapua. They are more or less identical with “264 USA Ackley Improved 30 degree shoulder”, don’t require fire forming and will work with standard 308W bolt heads.

  • Chris R

    So it’s ballistically similar to the Grendel which fits the AR15 platform. Not sure if this makes sense as it will mean a change of platform

    • It’s 200-300 ft/s faster than the Grendel with a given bullet weight.

      • Chris R

        But it would still mean a different platform. Makes more sense to run something that will fit the AR15/M16 platform. Who know’s advances in propellant may one day give the Grendel the extra horsepower.

        • But it is not ballistically similar to the 6.5 Grendel.

  • Russ

    The 6.5 Grendel seems superior to the 6.8 at more than 200 meters and to the 5.56 in every way except for the weight penalty and magazine capacity. What I have absolutely no knowledge on is how well a round links up for a machine gun and that is kind of essential for a do-it-all round. One other point that we forget is that a soldier may spend eight weeks in boot camp and eight weeks at infantry school and theoretically be shipped out to combat-that was a pretty accurate time line during Vietnam. The M16/5.56 were really well suited for that…less than ideal scenario. It could be we have found the sweet spot already.

    • 6.5 Grendel has a trajectory inferior to 5.56, up to 500 yards, when using barrels 20″ or shorter.

      5.56mm is well-suited to a realistic assessment of infantry combat, which is that the “superior marksmen picking off helpless enemies at a distance with small arms” idea is a myth. Other rounds may be well-suited to this, too, but it’s a mistake to act like poor training is the reason this fantasy hasn’t been realized.

      • russ

        You must be the first to describe the 6.5 trajectory as inferior. It may not be quite as flat as a hot 5.56 but we aren’t discussing varmint hunting. I’ll stand by my statement.
        The entire reason for this thread was to discuss the 6.5 in some iteration and less upon the merits of the 5.5. I believe I did mention that the 5.5 hits a sweet spot. Combat shooting involves marksmanship in most cases and all armies train to make their soldiers better at it whether the target is a point target (a man) or an area target (suspect position). You seem to be advocating that this is a waste of time and a return to musketry is in order. Or maybe mass waves of conscripts with cheap submachine guns?
        The fundamentals of marksmanship are a constant from zero to five hundred meters and beyond. If you give the soldier the tools to make hits at 200, you have already given him what he needs to hit at 500. He just needs to know his dope. I believe that would be the infantry half kilometer.

        • It loses about 50-70m maximum effective range vs. 5.56mm, according to the standards set by PEO Soldier.

          Shooting at the range is very different than shooting under stress. I can hit a man-sized target at 900 meters with my 5.56mm Colt 6920, but I’m not advocating a 900m infantry cartridge because I know the difference.

      • LilWolfy

        6.5 Grendel’s trajectory is more like 7.62×51 for elevation, but beats even the 175gr M118LR for deflection. I watch both rounds go downrange throughout the year, every year, and have been watching M118 and M118LR, as well as 168gr SMK through spotting scopes for 20 years.

        Impact on steel between a 123gr 6.5mm and a 168gr SMK sounds the same at 200yds, only it’s easier to hit with, follow-up shots are quicker, recoil is half, wind deflection is less, weapon weight is much less, etc.

        Once you put it in the hands of guys who are professionals, either having served in DM, Sniper, or machinegunner slots, you see the lights come on really quick. I actually feel cheated, and I hold Army Ordnance Board .30 cal nazis of the 1950’s responsible for the travesty that my back, hips, and knees paid for all those years.

        • At 70,000 PSI, I bet it has a better trajectory than 7.62×51. Further, trajectory to 500m and beyond 500m are very different animals. The former is much more important for individual infantry weapons.

      • Russ

        Well, that’s just simply wrong. At the ranges you insinuate, just about anything would be just fine as far as “trajectory” goes. You are actually the first person I have ever read criticizing “trajectory”. A 6.5 BZO’d would need no further adjustment in elevation with a center mass hold out to 300 meters. As far as marksmanship goes, the skills that score hits at 200 are the same skills that hit at 500. The difference is that little clicking bit on the back of the rifle. Hint: you look through the hole. See Monty Python’s “The Execution” on YouTube.

  • tirod

    Balance your joy over another brass cased cartridge with the knowledge that the LSAT is an advanced program with SOCOM as a participating member. Over 1,000 weapons have been produced and at the last open mention of it, Battalion level exercises were planned.

    Haven’t heard a word about it since, no news is good news.

    • Well, technically, .264 USA is a polymer cased round, too.

    • carcano

      Maybe they try to find the best intermediate cartridge for LSAT. They are working with both 6.5mm and 6.8mm cartridges. Maybe they try to find the best balance before they make the LSAT version.
      It would be a crime to start from scratch with LSAT and not even test an intermediate cartridge.
      I think if they have to start from scratch, it’s better to go ahead with just one caliber instead of having to make everything from scratch in the same two legacy calibers. There’s no need to design two lines of weapons and gear again, one for 5.56 mm and one for 7.62mm.
      With the benefits LSAT offers I wouldn’t be surprised if the lsat version of this 264 USA cartridge is just as light as the current brass cased 5.56mm round.

  • Secundius

    I’d rather have the 6.5 Creedmoor round, at least that has the range of the 7.62x51NATO round and the hitting power of the 6.5 Grendel.

    • Wh… What?

      • Anonymoose

        I kinda see where Secundius is going with this, I think. The smaller bullets would give lower recoil, which would mean better control on full-auto, and 6.5 could give power close to full 7.62 The Creedmoor is more of a ranged cartridge than a CQB cartridge, but the best CQB cartridge we have right now (balance of hitting power, capacity, and recoil) is probably .300 Blackout.

        • 5.56 is decidedly superior to unsuppressed .300 Blackout for CQB, especially if we include Mk. 318 and M855A1.

          As for his notion that 6.5 Creedmoor has “the range of 7.62 and the hitting power of the 6.5 Grendel”, it’s superior to both in both respects. That statement is just patent nonsense.

          • Commonsense23

            I am curious if you have heard any real world results of the M855A1. I have personally seen the effects of 318 and it is absolutely amazing, but have yet to hear anything outside of Gel test and press releases for the 855a1.

          • Not as much as I’d like, but initial battlefield reports are supposed to be positive.

            At the very least, it should have loads more penetration than M855, which was a weak point of that round.

            Mk. 318 is fan-fucking-tastic, I’ve taken two whitetails with it.

    • LilWolfy

      6.5 Grendel already exceeds the range of the M80 ball quite easily, with 8,000 less psi, from AR15 magazine well COL, using 123gr. Recoil is half of 7.62 NATO.

      • Depends what you mean by “range”. It has a lower effective range than M80 Ball for rifle applications, according to the definition set forward by PEO Soldier.

        • LilWolfy

          Maybe PEO soldier doesn’t understand effective range the way I do. The M80 will never stay supersonic as long as the 6.5mm 123gr will, even with a barrel length advantage.

          The M80 will never have the deflection a 123gr 6.5mm will, even with barrel length advantage. From an LMG or DMR or SASS user’s perspective, the 123gr 6.5mm wins. Then step up to a dedicated, purpose-built 130gr 6.5mm. It exceeds the energy of the M80 ball, and more importantly, the PKM, by 500yds.

          Put them both in soldier’s hands for a few days at the range and on FTX’s, and see which ones they hate, and which ones they love, especially when you go linked.

          Then run armor piercing tests. High SD with more speed wins. They both have more than enough energy within 500m. From thereon out, the 7.62 NATO starts to become a dog.

          • I’ve read the AA marketing material, thanks.

          • LilWolfy

            I’ve read my chronograph in front of my own 16″ 6.5 Grendel carbine, with BC’s that aren’t even what can be done with a 130gr dedicated LMG round.

            I’ve also sat in a patrol base while drafting better configurations for an LMG on the back of my cut down sleeping mat while in the prone, tired of carrying that albatross of a SAW, which is one of the true boondoggles in US small arms history.

          • Well, care to share any pictures?

          • LilWolfy

            Nope. Our enemies watch these discussions, and have already incorporated some of the design features that I have been talking about for years.

            Look at PKM modernization and you’ll see some features that are central to my overall design configuration, although mine is nowhere as crude.

          • Yeah, and they might copy your chrony setup, got it.

          • Kivaari

            At one point about 10 years ago, Valkerie Arms had a prototype of a quick change barrel RPD. Is that what people want? A 6.5x47mm-type LMG? Valerie Johnson was doing some interesting testing. Maybe she has pushed it farther along.

          • Kivaari

            When the kid was in Anaconda, he was a SAW gunner, except he never fired a round, not even in training, for the entire year. He could only say that while stateside the M249 wasn’t much of a gun. His unit had trouble making them work with M16 magazines. It didn’t work well. I guess it didn’t matter since he never did more than go on watch while white KIA pickup trucks out of range would flash by, while a mortar was fired from the bed.

    • marc

      The various 6.5-08s have a supersonic range closer to that of .300 WM.

  • Anonymoose

    Looks like it needs an intermediate-length (between super short, like a 5.56, and short like a 7.62) action. This isn’t going to work at all in an M4/M16, and is too short for an M-110/Mk17, so why bother? Why has no one tried necking 5.56 up to 6.5/6.8/7 and working with the powders to get performance?

    • Josh Carter

      Look up .277 wolverine. It’s a wildcat for now but so was 300 whisper

    • Powders pretty much all follow the same rules. The only way to get more performance is to raise pressure.

      Having said this, there was the 6.5×42 MPC, by SSK Industries, but I don’t think it went anywhere.

      • LilWolfy

        I would argue that there are more ways to get more performance than increasing peak pressure. If you elongate the pressure curve, without exceeding your working pressure, you will get more performance.

        This is where medium-slow powders pushing pills with long shanks comes into play. If you look over reloading data that included pressure, you can find powders that are much more efficient, as there are several that will produce more velocity with less peak pressure for a certain bullet.

        And the 5.56 has been necked up to .25, 6.5mm, & .277. There are at least 2 quarter bores right now. I’m not a big advocate of messing around with 5.56 other than projectile evolution, and maybe some critical component upgrades, since we don’t shoot the cartridge it was engineered around anyway. 5.56 works very well for the duty positions it fills.

        7.62×51 NATO is, and has always been the problem in dismounted small arms weapon weight and logistics. The .264 USA would blow it away as a machinegun and sniper cartridge quite easily, even handicapping it like they seem to be doing with the listed speeds. The shoulder angle isn’t helping them either at 20 degrees, although I know they think they need that for reliability. Maybe someone should show them a Swedish Army 6.5×55 BAR, or some of the Swiss service rifle cartridges with a 30 degree shoulder.

        The 6.5 Grendel with 30 degree shoulder runs fine on auto, and semi auto in a gun it was shoehorned into. I just don’t have malfs with it, and have owned it for over 5 years now. The 30 degree shoulder would do a lot to increase efficiency of burning the powder column, like it does with 6.5 Creedmoor and 6.5×47 Lapua as well.

        • You can only elongate the pressure curve so much in a gun. There’s really very little margin here. Look at Hodgdon’s pressure safe data, which is through a 24″ barrel. 6.5 Grendel is running about 2,500 ft/s. That comes out to about 2,310 ft/s from a 16″ barrel, if we generously assume 25 ft/s loss per inch of barrel. So your 2,700 ft/s figure is way above that. Hodgdon’s figures are running 50,000 PSI; I would expect your load to run close to 70,000 PSI. You might well not see any pressure signs from this; primer yield strength can be up to 76,000 PSI.

          There’s a mistake here in thinking that because the pressure curve can be manipulated somewhat, that something can be had for nothing. This is not true. With powder optimized for the barrel you’re using, what you get for a given pressure is pretty much what you get. There’s a little bit of wiggle room for thermal efficiency here, and some cartridges lose more to waste heat than others, but most modern ammunition shooting OTM bullets are going to be very comparable.

          The big innovation in recent powders is thermal and long-term stability, allowing the peak pressure to be raised without danger.

          CFE223 is basically commercial SMP-842, that is what M855A1 uses. There’s nothing magical about it. There’s nothing magical about the Grendel, either. If you’re running velocities that high, you’re running pressure that high, too.

          • LilWolfy

            Hodgdon’s doesn’t have data for CFE in the Grendel, but Hornady does in their 9th Edition. I think you will find it interesting, especially since it’s for an 18″ barrel. They maxed at 2500fps with the 120gr GMX, which is a copper solid with the bearing surface like a 140gr 6.5 cup & core pill.

            When you use the max load for a 129gr cup & core for a 123gr, you get 2532fps from a 16″ barrel, and you are well under the already low working pressure. The max load for a 123gr cup & core will get 2572fps with CFE from a 16″ barrel currently, and we’re only at 52ksi there. For a SASS system based on the AR15, you could easily match this .264 USA cartridge performance parameters, with very minor tweaks in the cartridge components, without really pushing the pressure either.

          • Case volume does not work that way, put simply. What you’re suggesting is that you can get something for nothing here. That’s not so. It won’t ever be so with the current state of the art, no matter how many times Grendel fans post that they can do it.

            Using CFE 223 gives a 50-100 ft/s increase in velocity for most cartridges. The 6.5 Grendel isn’t an exception. Claiming that the 6.5 Grendel can do what the .264 USA can do at the same pressures is utter nonsense.

            I haven’t seen Hodgdon’s 9th Edition reloading manual, but I have seen load data for the 6.5 Grendel with CFE 223. It looks a lot like Varget. That is to say, nowhere near your unsafe numbers.

            Velocity comes at a cost. That cost is pressure – pressure is literally what pushes the bullet forward. Of course gains can be made without raising pressure through making the gun more efficient (e.g., insulating the barrel, reducing frictional losses) or the pressure curve longer (which only works up to a point, and you’re pretty much at that point by using a modern powder appropriate for rifle barrels), but there’s also a lot of confusion about pressure.

            For example, 5.56mm NATO is specced for about 58,000 PSI MAP. What this means is that the average pressure of a lot of ammunition when tested cannot exceed 58,000 PSI. The actual pressure generated by each individual cartridge when firing may be much lower, down to about 48,000 PSI, even. In fact, take one cartridge, fire it in extreme heat, and it can generate up to 90,000 PSI (no kidding), or take it into extreme cold, and it can produce only 40,000 PSI or even less. But the MAP stays the same for 5.56, despite this wide variance.

            Now we shift to the handloader. He has every advantage. He does not have to test lots for consistency in extreme temperatures, he doesn’t need to make sure he can load a billion rounds per year under the MAP limit, and he can tailor his load to his gun. Maybe he whips up a real whiz-bang load; it tips the scales right at 58,000 PSI (we’ll say he has a strain gauge), but it’s 150 ft/s faster than NATO spec ammo. Of course it is, because that load doesn’t have to work and be safe ten billion times in a row in five million different rifles and still meet the requirements.

            So maybe you can handload the 6.5 Grendel to match the performance of the .264 USA within safe pressures (which I frankly doubt; seriously back off that load, dude), but until you load a billion rounds of it (hell, even ten thousand would be nice) and test fire it again and again from hundreds of rifles coming off an assembly line as fast as it can go, you really can’t make this comparison, now can you?

          • LilWolfy

            Hornady’s 9th, not Hodgdon’s. I already listed the data for Hornady and CFE223. I know very well how case volume works. Suggesting getting something for nothing is a straw man fallacy, as that isn’t part of my position – a gross violation of physics.

            There are some powders that are more efficient with a particular case and projectile combination, as I think you are aware. There is no need to erect straw men arguments in an attempt to claim the higher ground.

            I also agree that the larger case, all else equal, is going to have more potential for velocity. The loads I mass produce are well below the MAP, and have much tighter Extreme Spread than most factory ammo. Varget behaves nothing like CFE223 in the Grendel case. It’s too bulky for its burn rate. CFE fills the case extremely well, and seems to have the ideal burn rate for 123gr pills. I am below Hornady’s book max for even 129gr (which have longer bearing surfaces, same jacket alloy and construction-same mfgr).

            Most cartridges that CFE is used in (we’re mainly talking .223 Rem and .308) don’t have a 30 degree shoulder. 30 degree shoulders are a known efficient column burner, since there is more resonance off the inside of the shoulder back into the case. CFE also exceeds most other propellants in charge weight due to the way it fills the case, so instead of maxing out at ~28.0gr, book loads max out at over 31.0gr. Remember, we’re still way down below 5.56 and 7.62 NATO pressures, due to the AR15 barrel tenon restrictions.

            Using a larger tenon, and military canister powders engineered for the case and projo combos, it would not be hard to meet the .264 USA specs, although I do agree on large batches needing margins for Maximum Average Sample Mean, and the extreme ends of the margins in manufacturing-no argument there. That doesn’t seem to deter insane loads for 5.56 NATO, but it is in fact a bad practice to push to MAP’s anywhere near 62ksi in a military cartridge. M855A1 is a major violator in that regard.

            I have discussed these issues with Hornady’s ballistics engineers, the guys who run the pressure test equipment, Hodgdon’s tech assistants, several other engineers with pressure test equipment, and the engineers at Lapua. CFE is a very forgiving powder that produces speeds a bit better than AA2520 in the Grendel, with much less sensitivity to temps. If you look up AA2520, even at 50ksi, it generates 2630fps from a 24″. The loads I produce are under MAP, with tight ES.

            But I do agree that 5.56 is way over the edge in pressures, especially with your ammo in the heat examples. Been there, done that with M855. 5.56 NATO MAP is also 62,000psi, not 58,000, although most companies prefer to stay in the mid 56-58ksi range. This brings me back to my advocacy of DM loads, and LMG loads with increased COL for a belt fed. Black Hills currently makes awesome ammo with very tight ES across the lots, and lot-to-lot. There is already a precedent for the industry to be able to maintain very tight standards for DM/Sniper cartridges. 5.56 NATO should remain an assault rifle/carbine chambering. It is 7.62 NATO that needs to go away.

          • Muscle memory – I knew you said Hornady.

            What you’re doing with the 6.5 Grendel isn’t possible with military ammunition (not in an AR-15 anyway). I suspect what you’re doing is also too hot for your gun, but you seem confident in it.

            CFE 223 is an excellent powder, but it’s not magic. It doesn’t produce velocity where there was less before. It’s more forgiving yes, which is why they use its military counterpart in M855A1 (which is, by the way, very safe, since it actually experiences a tighter band of pressure extremes than WC 846).

            Suggesting that we can get the performance you’re quoting from a military 6.5 Grendel is what I’m taking issue with here. Yes, the Grendel is well-designed from an efficiency standpoint. Yes, CFE 223 is very forgiving for the loader. Yes, your rifle probably hasn’t blown up yet. But that doesn’t mean that load is ready to be produced at a billion-per-annum production rate.

            Further, it doesn’t seem like you really grokked what I was saying about military specifications and pressure. You’ll have rifle cartridges that, when fired, produce 58,000 PSI and 3,100 ft/s with 62gr bullets from a 14.5″ barrel, and some that produce 45,000 PSI and 2,750 ft/s from the same length barrel. That’s what the spec exists for, is to give that allowance. If your rifle cartridge produces the velocity you’re talking about only at close to MAP when carefully handloaded, it’s not suitable for military use. period.

          • LilWolfy

            Again, I’m below the maximum load for a 129gr Hornady SST, but shooting a 123gr Hornady, and still easily over 2500fps from a 16″ barrel. The max load for a 129gr puts me at 2532fps with a 123gr, so I’m below the MAP at ~48,800psi with that load. If I work up to 50,000psi, I’m around 2550fps, and 51,500psi puts it at 2575fps.

            And I do understand the margins of a bell curve for mass-produced military ammo. I’m talking about a limited production load on the scale of Mk.262 for DM’s and SASS, not M855 volume. I’m also talking about building a new AR carbine around the cartridge, rather than stepping up to the AR10 albatross.

            The LMG with a larger barrel tennon and longer allowable COL would also have more leeway in how the cartridge could be loaded, with an optimal projo base in the neck-shoulder junction. One thing I have come to appreciate though, is that the general COL limitations of the AR15 magazine well force us to work with something that bodes well for the soldier’s load. Once we start to push past about a 2.4″ COL, the ammunition profile weighs heavily away from the C of G of Joe, especially with a projectile outwards orientation in the pouches.

            I see that you are a proponent of 5.56 NATO, as am I. It sold me on its performance numerous times in real-world terminal ballistics examples on both enemy and friendly incidents (blue on blue), so maybe I need to clarify that 7.62 NATO is what I want to see phased out with a 6.5mm for both LMG’s and DM/SASS weapons, while the majority of soldiers still retain the 5.56 NATO carbine.

          • “2675fps is already doable with an optimized 6.5 Grendel load underneath the 123gr SMK, from a 16.7″ barrel.”

            This is the performance estimate I take issue with. two thousand five hundred and something ft/s is another thing. That’s “a little hot”, but 2,675? Get out of town.

          • LilWolfy

            I stand by the statement that 2675fps is doable with an optimized 6.5 Grendel with the 123gr from a 16.7″ pipe, if someone wants to build an action and magazine around those performance requirements. There is no need to change the case dimensions. Simply push the COL to 2.4″, with a slightly larger barrel tenon, upper receiver, and a mag and lower receiver that are purpose-built around those dims, and you’re done.

            There are 20″ Grendel bolt guns that will exceed that speed with a 129gr. A 20″ AR15 with factory 123gr Hornady can already hit 2600fps, with pressures at around 49,000psi as tested on pressure trace equipment.

            My 2532fps load is nowhere near hot, at 48,8ksi. The .264 USA, given the case capacity, would be able to achieve the performance they are listing with pressures well below 50ksi, which is why I wonder if it is a proof-of-concept for the hybrid polymer case with steel base-cases that don’t do so well with pressures above 50ksi.

            I’ll tell you a load that is hot, that is being produced in very large quantities right now, and that is the Mk.262 77gr. It will deadline M4A1’s if you run it in volume through them, and that has been proven by a very misguided command who thought it would be a good idea to run that load for multi-week CQM and CQB courses.

            We are running pressures through the AR15 with a cartridge it was never engineered around (5.56×45), since the cartridge didn’t even exist when Jim Sullivan and Robert Fremont designed the AR15 around the .222 Remington in 1957. The whole gun would do well to undergo a re-design in the critical pressure containment components, as well as a slight COL increase, and that applies to just 5.56×45, since it has a longer COL than .222 Rem.

          • Doable by a handloader under controlled conditions via a gun that’s not feeding from the magazine.

            That is not the same as doable while being suitable for a military round.

            Pressure is not the primary worry here; Mk. 262 has less bolt thrust than the 6.5 Grendel at 49,000 PSI.

            Change the pressure and OAL specs to achieve your imaginary unicorn performance and it’s not a 6.5 Grendel, either.

    • ClintTorres

      6.5PCC…I was seriously considering getting one(all one needs is the barrel just like 300BLK)…oh, and dies.

  • Court Spotts

    My les Baer .264’s accuracy and ballistics has sold me big time…

  • Fintan

    And we’re right back to the .276 Pedersen. All old ideas are new again someday, right?

    • Right, neither of which are all that different from 7.62 NATO in any case.

  • gunsandrockets

    .264 USA? Here we go again. It amazes me the energy expended to create some ‘ideal’ rifle cartridge without any actual results, particularly by the US Army.

    Why not just adapt the ancient .250 Savage cartridge and call it a day?

    • It’s not that much more difficult to order a new reamer than it is to order an existing one. I guess they could have made a .260 Remington or .250 Savage or something similar if they wanted to. Maybe they did, and this is their follow-up.

  • herb

    When will everyone realize as I do that .257″/6.3 mm is the optimal projectile for military small arms?…

    Jk. Kind of…

  • Why didn’t we just adopt .280 British way back when? Pretty much the same general idea and probably very similar ballistics. Oh wait, silly me.

    • Ballistics are very different (the .280 British has a relatively poor bullet shape and lower velocity). The .280 didn’t meet the requirements of the period, and still doesn’t today.

  • Kivaari

    .260 Remington? 6.5mm/.308? 6.5mm (insert name of wildcat here). Look back at the Mauser rifles all using a 57mm long case. Mauser had cartridges from

    • .264 USA is based on a lengthened 7.62×39 case.

      • Kivaari

        l pay attention in class. So, its just another 6.5mm Mannlicher Carcano/Greek/ Rumania/what ever. My point is nothing is new.

        • I’m not that clear on what your point is. Yes, there’s little new in the way of metallic small arms cartridges, but you seem to be under the impression that I either think this is the best thing since sliced leavened bread, or that I shouldn’t report the news if the news isn’t exciting and different.

          • Kivaari

            Not at all. I’ve seen so many new ideas come out since I was a kid in the 50s, that not much shows much ingenuity. This is a 6.5x47mm cartridge, if my math is right (25.4 mm per inch and 1.87 long case) means it is a shortened 6.5 Carcano. As you know the 6.5x(insert case length here from 50-54mm) has been around since 1890. I had always contended that the 6.5mm Italian round was an excellent cartridge, had it been loaded with a Pointed-boat tail-120gr bullet).
            I played with it 30+ years ago. In circa’89 I received a report from Dr. Fackler where his research team at the Presidio SF, had tested the Italian load. I have one of the original computer created bullet track records. Fackler wrote me that his intent (before publishing the official report) was to see if an Italian doctor circa 1900, had used techniques that could be judged against modern testing using ballistics Gelatin. He reported that at that time it was the farthest penetrating military rifle round the US Army had tested.
            He went on to report on bullet wounds of the .30 US (,30-40 Krag).
            Fackler was truly impressed with the doctor’s work 90 years earlier.
            Fackler was a combat surgeon and specialized in vascular reconstruction. He knew is stuff.
            He recounted medical reports of US Army soldiers hit in muscle or
            lung (w/o BONE IMPACT ON ENTRY), They could return the soldier to duty in 2 weeks. All in the pre-antibiotic era.
            Small bore 6.5mm, 30-40 bullets encountering muscle and were so stable wounds were minor.
            The Mannlicher case is home to any bore diameter from 5.56 and up to 7.35mm.All the big differences in the Balkans region where each army had the same case just with a longer neck.
            I am happy with 5.56mm.
            Many nations have studied these caliber from 1919, Russia had a 5.6x39mm case prior to the outbreak in 39, The swiss were on it pre-WW2 as well, Russi had a .223 round, Switzerland had several 7.5 AK sized case before WW2.
            I like these articles. Tonight ,I was just too tired to read clearly.
            If yu can find your bood, look up the .280 UK, the .276 Pederson, 6.8 SPR. I like reusing the Italian information in modern AR-style rifle.
            Me, I am an old timer that can live with the 5.56mm NATO or the 55 gr.M193. I’ll b dead before I can shoot all three rifles I have in that caliber. I have high praise for Colt, Bushmaster and Bravo Co.
            Good gear wrapped in Magpul furniture.Great products.

          • Here’s a picture of some .276 Pedersen ammunition that I own:

            http://i.imgur.com/eJGLTt5.jpg

            They’re on an SKS stripper clip because… Why not?

          • Kivaari

            No intent to say anything negative. I just wish our army had paid attention

          • If we’re talking about 7.62 NATO, I agree. That was a silly decision that really stayed ignorant of even previous US research.

  • Giolli Joker

    Wake me up when we hear some update on CTA trials…

  • LilWolfy

    6.5 Grendel will already push a 123gr to 2700fps from a 16″ barrel, with the right powder and a gun built around it. There is no need for that long of a cartridge to meet that speed, and that’s staying withing the AR15 magwell COL. Propellant advancements have come a long way in the last few years.

    No way do I want every soldier carrying anything like that kind of performance. This 6.5 USA cartridge would make sense for DM’s, but it still looks to be larger than needed for the soldier’s load, especially if we look at LMG’s as a possible platform for chambering.

    It’s a huge improvement over 7.62 NATO though.

    • No it won’t.

      • Alex Nicolin

        Currently 6.5 Grendel pressure is constrained by the AR15 platform (barrel shank diameter, bolt thrust) to around 52 KPSI. But with a thicker barrel shank and a bigger bolt face, and a short action it can be run at the same pressure as the 7.62×51 mm (61KPSI) or even 5.56×45 mm (62KPSI). At this point, it would be pretty close to the .264 USA, while being more compact, lighter and having better performance from shorter barrels. I would have to run the number, but I reckon there would be less than 150 fps between them when loaded with the same bullet (110 to 115 grain FMJBT with partial steel core).

      • LilWolfy

        With CFE223, it produces about 200fps more than I thought it would. Factory loads from multiple vendors average 2450fps with a 123gr from a 16″ barrel. CFE223 achieves that without even trying.

        CFE223 is so forgiving, that I reached 2700fps, but was scared the next incremental charge weight, but it showed me that with the right set-up, it would be easy to do.

        There is a rifle on the market right now that has open architecture to use as a perfect testbed for these types of trials, to include the .264 USA. It’s an AR with DI, but has been overlooked by a lot of people.

        Once they settle down on a cartridge, whether polymer, metallic, a dedicated canister powder optimized for the case volume and projectile shank + weight in the rifling can generate plenty of velocity behind a 130gr cup and core, or a 105-115gr solid, and still keep the pressures low.

        My first temptation was to push the pressures, but why do it if you can achieve target-based terminal effects with a lower pressure system? Pressure beats machineguns and self-loaders up, erodes throats, and amplifies the margins in QC, especially on a military scale.

        • Back off your load. You’re certainly running the pressure way up.

  • ClintTorres

    How about a little poll?

    If you got to take ONE of the above cartridges to war with you, which would you choose? (Let’s assume in a magazine-fed, auto-loading rifle).

    I suppose I’d go with the .264USA.

  • Blake

    I’d be interested to see a comparison chart between this & the plethora of other 6.5mm cartridges available. Just as an example, 6.5×47 Lapua was specifically designed so that firearms chambered in 7.62×51 NATO could easily be rechambered for it.

    Personally I think that the best place to concentrate research effort is in designing actions & cartridges that can handle higher case pressure so that faster powders can be used, which enables shorter barrels & gas systems…

  • anon

    So when will we be getting those telescoped rounds that the LSAT program promised?

  • jay

    I hope they get the data they need from this and use it in the LSAT project. When they go to LSAT, I’d rather see them go ahead with a single caliber, instead of having to make from scratch, two new lines of products in two calibers.

    • If it were feasible, I should agree. I really don’t think they’ll reconcile the requirements of the MG and rifle, though, especially if they’re gonna wrap .50 up in it, too, which is something I’ve seen mentioned.

      • mig1nc

        I agree with Jay too. A CT round in this caliber would save the necessary weight and space to get the warfighter’s combat package back down to reasonable numbers.

        • Recoil’s a big factor here, too. A CT variant of .264 USA would have recoil equal or greater to 7.62x51mm, due to wasted propellant gases (an inherent trait of that form of round), and given that was arguably the biggest single factor in the change from 7.62 to 5.56mm in rifles, I don’t see it replacing 5.56mm.

          • mig1nc

            Very interesting. The only notes I’ve read on recoil were for the LSAT LMG where they claimed good characteristics. Do you have an article I could read where recoil characteristics of the round are discussed? I’d love to know more about it.

          • I’ll have to dig up the NDIA presentation where they were saying LSAT ammo (both varieties) required something like 30% more propellant to achieve the same performance. This was considered acceptable since the ammunition gets so much lighter and smaller. In the case of the .264 USA, though, it would negatively impact its already marginal recoil characteristics.

            Having said this, it’s possible LSAT has solved this problem, I am not on the inside and couldn’t say for sure. But I think it will always be there in somve way with the telescoped layout, if a sabot isn’t used.

  • LilWolfy

    2675fps is already doable with an optimized 6.5 Grendel load underneath the 123gr SMK, from a 16.7″ barrel.

    Build a carbine around that performance, and you could use the existing 6.5 Grendel case easily. There is no need for that case length, unless you want to reduce the pressures, and that may be exactly why they have configured the cartridge this way.

    If the case is meant to be a baseline testbed for polymer or hybrid cases with a steel head and polymer body, then lower working pressures may be reason for this case geometry.

    Keep it down at ~45,000psi, and you have plenty of case volume to work with to achieve those numbers. It also might explain the shoulder angle, since a more efficient 30 degree angle may not be ideal for polymer, and induce separation in that area, particularly in a loose machinegun chamber.

    In that context, this case set-up makes a lot of sense to me. As a metallic cartridge, it is too large for the stated performance requirements.

    • That level of performance is not safely achievable from the 6.5 Grendel.

  • UltramanSuperdude .

    What about the 7x46mm UIAC cartridge that was mentioned on this blog a couple years ago?

    • That is a non-governmental effort. It’s mentioned in the article.

      • UltramanSuperdude .

        My comprehension skills need some work. So you say that the two are pretty similar when it comes to ballistic performance eh? I doubt that either will be selected and it wouldn’t be the end of the world if that were the case. Many have already mentioned the need for marksmanship training and good hit placement.

        • 7x46mm is a little worse, ballistically, but it’s also a little shorter.

          Current marksmanship training is very good. There’s a misconception that being able to hit targets at the range translates to the average soldier being able to hit a target in combat at range. This isn’t so; even with “expert” level marksmen under the traditional marksmanship standard (pre-Vietnam), hit probability becomes almost negligibly low after just 100m.

  • Anon

    .50 BMG–the B is for bullpup–all you need

  • I don’t know why a brand new cartridge is being developed when there are so many really good existing cartridges out there already. Some have already mentioned the 6.5mm Grendel. We all know how hard it is to convince the US military to adopt something new that would make things better. I think the .26 caliber bullets are great and there are a lot of good bullet designs out there for that caliber.

    • The 6.5 Grendel is not suitable as a military rifle cartridge, except with very light bullets.

  • billyoblivion

    The problem isn’t the boolits or the boolit lanchers, the problem is trigger time and ROE.

    Those units that train hard and well with their rifles get done what needs to get done when they are given the appropriate ROE.

    I’m not against progress mind you, but there’s *LOTS* of good designs already out there, both bullet, case and launcher. Stop wasting money on bureaucrats and start spending on on marksmanship *and* combat training.

  • Colin

    6.5mm great bullets 80gr -168gr .NOT too small to hunt deer,moose Etc with, big anoth for ballistic carry to a 1;000 yards .better A.P. then 7.62. NATO smaller cross section ,penetration more, longer bullet ,,ballistic better ,( Compare same weight 7.62 vs 6.5mm) Just ask the 1;000 Yards F CLASS Boys & Girls what they Use…Why not use 6.5x47Lapua .same size head as 7.62 equipment but better bullets, lighter cartridges, longer bullets for same C.O.A.L. (7.62 NATO) ,Can you imagine M60 E6 6.5x47L 155gr FMJ Lapua ,back pack fed plastic link? Routing tooting bad ass suppression yes/no ? Snipers with Rem Csr 14″ Carbon barrel 7″ suppressor Lw 1,000 nail gun (F Class). Desert Tech Mdr 6.5 + suppressor (suppression works best smaller the round )with Either six12 /870Mcs breacher oR 40mm ugl. OR DO we wait for a Full On 6.5 LSAT SYSTEM cased or caseless . DISCUSS BUT BE NICE I AM ENGLISH AND UNDERPRIVILEGED IN FIREARMS BY LAW!!