Modern Personal Defense Weapon Calibers 002: The 4.6x30mm HK

Four PDW calibers: .22 WMR (Kel-Tec CMR-30 and PMR-30 SMG), .22 SCAMP (Colt SCAMP), 5.7x28mm FN (FN P90), and 4.6x30mm HK (HK MP7).

Four PDW calibers: .22 WMR (Kel-Tec CMR-30 and PMR-30 SMG), .22 SCAMP (Colt SCAMP), 5.7x28mm FN (FN P90), and 4.6x30mm HK (HK MP7).

If the 5.7x28mm FN is the first successful modern PDW round, then the 4.6x30mm HK is the second, and its biggest rival. German firm Heckler and developed the microcaliber 4.6mm in the 1990s as a response to a NATO solicitation for a Personal Defense Weapon, to which they submitted their new HK PDW (later MP7) chambered for the new round.

The 4.6x30mm HK is an 0.18″ caliber round firing bullets of much the same weight (but inferior ballistic shape) as the 5.7x28mm, but at slightly lower velocities due to the MP7’s shorter barrel.

It is compared to the 5.7x28mm FN and the 9x19mm NATO in the charts below:

oM7FXnZ rKc04dm aF15jum

Overall, the 4.6x30mm suffers the same problems that the 5.7x28mm does, those being poor energy retention and mediocre wounding capability. However, the 4.6mm does improve on the retained specific energy (energy divided by frontal area, an important consideration for armor penetration) vs. the 5.7x28mm. Therefore, I would expect the 4.6mm to be the superior armor defeater, with the 5.7mm having less poor terminal effects.

Due to its very similar overall characteristics to the 5.7x28mm FN, the 4.6x30mm will likewise have very similar recoil characteristics, and therefore I will omit that section for this post. For all intents and purposes, they are identical in terms of recoil.

Likewise, in terms of weight the two calibers are also virtually identical for a given projectile weight, at about 6.5 grams per shot.

Between the two rounds, I agree with the conclusions of NATO testers that the 5.7mm is overall the better cartridge. The choice of a 4.6mm bore diameter on HK’s part is in my opinion a “bridge too far” for the small PDW cartridge concept, and is the major limitation of the round with respect to manufacturing, internal and terminal ballistics, and other characteristics. The perforation advantages of the 4.6mm caliber don’t seem to be very significant, and the same effect could also be achieved with the 5.7mm via an improved core or a sabot loading, anyway. Most significantly, though, the 4.6x30mm HK is – due to its small bore – essentially incompatible with modern service pistol designs.



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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  • Evil_Bonsai

    I’ve seen the ‘NATO request for PDW’ more than a few times, previously owning a Five Seven pistol and reading up on it’s development. Did anything every come out of this ‘request’? Did FN and H&K both develop a PDW caliber/weapon system (for FN, anyway) to which NATO decided “eh…nevermind”? Does NATO have a specific PDW in use? Personally, I love the concept of such calibers (short, bottlenecked, supersonic), but seems NATO decided to stick with either 5.56 weapons or 9×19, as needed.

    • Trevor

      I read a long time ago that they had almost agreed on 5.7 but Germany protested and jammed the whole process up. I wish we would have seen 5.7 adopted by NATO so we could see some more 5.7 caliber firearms and cheaper 5.7 ammo process.

      • Kivaari

        Ruger could have done in on the small 77 action. Now the little ones are no longer made. That 77/357 action in 5.7 should have sold pretty well.

    • Joseph Goins

      The concept behind the PDW was to arm aircrews and non-infantry frontline troops, but the acceptance of the M4 is what killed the idea. When the PDW mindset was created, the only thing that NATO countries had were full-size FALs, M16s, FNCs, AR70s, G3s, and AUGs. The FN P90 was first wielded in 1991 before the M4 was in service. The M4 was small enough to stash in helos, tanks, and HMMWVs.

      • iksnilol

        AUG with 16″ barrel is a bad example of cumbersome rifle to use.

        • Gun Fu Guru

          Only in terms of length. The rear portion is very tall.

      • ostiariusalpha

        That’s a good point, though the end of the Cold War had the largest effect on keeping the PDW rounds from adoption; no need to penetrate the vests of Soviet troops when there is no Soviet Union. The development of the very compact 5.56x45mm rifles, like the Mk 18, has put an even bigger crimp on their future.

        • Joseph Goins

          That’s a decent hypothesis, but their body armor was being spread as fast as their rifles following the collapse.

      • Joel Negron

        Didn’t the MP5K-PDW fit a similar niche as well?

        • Joseph Goins

          Size wise? Sure, but it wasn’t commonly adopted. I also doubt whether it could have penetrated the Soviet body armor which was one of the main requirements.

      • valorius

        The P90 is far, far more controllable in full auto fire though. They’re not really comparable in that regard.

        • Joseph Goins

          Which is probably the least important criterion for issuing a new weapon.

          • valorius

            Which is of course why assault weapons are all select fire.

            Do you know what suppressive fire is?- asks the ex infantryman

          • Joseph Goins

            Yes. – Replies the retired 11B (1/75th) and 38A (95th CA Bde (A)).

            Controllability in full auto was not a major criterion for accepting the PDW concept. I’m not saying that the P90/MP7 is better in this regard than the M4, but it didn’t substantially factor into equation of arming non-infantry combat troops.

          • valorius

            Actually it was- Even back as far as the M1, which was originally intended to be full auto until the Army realized a 5lb gun is uncontrollable in full auto fire with the .30 carbine round.

            Suppressive fire is extremely important for support troops trying to break contact and escape an over-run situation, eh?

            I’m ex 11B too, thanks for your service.

          • Kivaari

            I feel the M2 carbine is not bad for control. Like a lot of the SMG sized guns once the initial shove is compensated for you can run ’em like a water hose. Same for a 13 # TSMG.

          • valorius

            The original M1 spec, before the M2, called for full auto capability. It took til the M2 for them to get it to work.

            As early as about 1938-39 Auto Ordnance submitted a fully functional .30 carbine chambered Tommy gun (weight was typical for a tommy gun). Would’ve been America’s first assault rifle, years before the Stg44 and a good 25 years before the M-16…but the Army Odnance dep’t didnt’ realize what they had in front of them, and said thanks but no thanks.

            Ooops.

          • valorius

            PS- 4/31 infantry.

      • Kivaari

        AND an M4 fires are real cartridge and not a toy cartridge.

  • PK

    Your expectation that the 4.6x30mm is better against armor, even at moderate distance, than 5.7x28mm is entirely justified. Good call, but it’s important to know that with the same projectile construction they are incredibly close in ability.

    I’m of a very similar opinion as you are… I wanted to like this
    cartridge, I really did, but when even a barrel blank is a special order item with a multi-month
    wait, it’s hard to get a build started.

    Now, if there were a ready solution to buy off the shelf, a semi-auto MP7 for example, my opinion might change.

    • valorius

      4.6mm should be better just by virtue of having a smaller diameter.

  • micmac80

    Even tough 5.7mm had inital head start and earlier acceptance ,SOF are now days using the MP7 much more than ither P90 probably due to ergonomics.

    • PK

      To be fair, the MP7 is much more compact than the P90. Lighter, too. Also, it’s not feasible to holster the P90, although it is hilarious to try.

    • I suspect it’s the ergonomics and more importantly, the magazines, that have made the MP7 more popular the P90.

      The MP7 is 16″ long to the P90’s 19″, which is not much of a difference.

      However the P90 magazines are unusually long – they are 1.5″ longer than a 42rd 5.56 AUG mag. And, the P90 is much slower to reload.

      • TexianPatriot

        This exactly.
        The P90s ergonomics are excellent, if you only need one magazine. Mag changes are ridiculous, and the mags are huge. It was a good try, but fell short.

        • iksnilol

          They should make a quad stack 100 round mag for the P90. With 100 rounds on tap you don’t need to reload (at least for most folks it is intended for).

        • valorius

          my old man has a P90, i love it.

      • valorius

        It holds 50rds, what are you doing that you’ll need to reload?

        • For a civilian use (which is where I think the PS90 truly excels) there is no need.

          For SOF guys, especially those working in small units behind enemy lines, reloading is likely an important issue.

          But even more than the reloading, I think it’s likely an issue of just trying to carry spare mags. The things are crazy long, and due to the protrusion of the rotating feed tower, they cannot be “double stacked” in a double mag pouch the way flat AR/AK/MP7/etc mags can.

          I’ve yet to see a P90 mag pouch/chest rig that didn’t look super awkward.

          • valorius

            They sell tac vests that hold 4 50rd P90 mags. So with one in the gun you have 250rds.

            I agree the P90 is not as fast to load as say, an AR, but with a little practice it’s certainly much faster than, say, a revolver.

    • valorius

      because according to poster common sense, you need 20 rounds center mass to stop someone with 4.6mm (LOL)

  • iksnilol

    They should neck 5.56 down to 4.6. Just for giggles.

    • ostiariusalpha

      The .17 Remington gets pretty close to that idea.

      • iksnilol

        I like it… hey, somebody! Make very low drag, high BC bullets for this… please ?

        • Edeco

          I wish, I went thru a phase of being obsessed with the idea of .14’s. I suspect there’s relatively a lot of friction to the amount of rear cross section as bore gets smaller, so the ability to accelerate them is geometrically derped, compared to what were used to. Not 100% sure, in some situations the contact patch matters more, some less.

          • iksnilol

            eh, .17 remington didn’t have problems getting the velocity up. Only problems with keeping it at distance.

          • Edeco

            Exactly; the normal bullet has the SD a dried maple leaf, is easy to accelerate or decelerate. I think the velocity with a heavier bullet would be unimpressive tho, with high erosion and fouling.

          • iksnilol

            What about a long slender copper bullet with steel tip?

          • Edeco

            So high BC, similar weight… I dunno, now that you’ve got me thinking about it, I’ll have to plug a high number into a ballistic calculator. I’m continually impressed with the new apparently high BC bullets that keep coming out, the alleged performance anyway…

          • iksnilol

            Exactly that. Same thang, just ramp up the BC and shiznit. Probably wouldn’t fit an AR mag but c’est la vie.

          • JSmath

            Eh, just neck the shoulder down earlier. Not like anything in .17 cal is really, *really* going to need over 16″ to get to much more than diminishing returns of a 5.56 case worth of powder charge behind it.

          • Kivaari

            fouling and barrel wear. AT 4000 FPS no barrel lasts long and I don’t know of any bullet material that wont foul, or if it wont foul it has to wear the barrel out fast.

      • Kivaari

        The .17 Reington is known to foul bores in under a box of rounds (20). In a service weapon it would be terrible. Think about them as being over-driven BBs. The AP rounds will need to really tumble to be very effective. Too bad there are no REAL AARs telling how these worked in the field. The only source I read where these were used the SEAL said they used them with the suppressors and shot sleeping Taliban in the head. There was no mention of them using them “in combat”, just what amounts to an effective assassination. Does anyone have real evidence of these things being used?

    • BrandonAKsALot

      22 eargesplitten loudenboomer! Just neck that down further to accept 4.6.

      • iksnilol

        That’d be kinda not practical. :/

        • BrandonAKsALot

          Not practical? ! A .50 BMG necked down to anything is always a great idea.

      • Kivaari

        Wasn’t that essentially what the experimental British round was? Somewhere around 4.85mm on 5.56mm case.

    • JustAHologram

      Or a .30-06

    • Paul White

      no bore like overbore

  • ostiariusalpha

    Hmm, I do wish you had been able to elaborate on that last sentence just a bit more, the story of the HK P.46/UCP would have been worth at least a paragraph. And no mention at all of the 4.6 Radway and its Löffelspitz (spoon-tip) bullet? There’s no need to get side-tracked with historical trivia, but both its existence, and that of the 4.6x36mm cartridge that was the precursor to the 4.6x30mm, could have been acknowledged with a sentence. Other than those nit-picks, this was another excellent article covering the practical aspects of the 4.6mm round. Great job, and thanks for all your devotion to these subjects!

    • Thanks for reading. Honestly, I have to pick and choose what goes into these articles; they are not intended to be full historical dissertations, just ballistic profiles.

  • Justin Roney

    I would wager a five round burst to the chest would still ruin your day.

    • Major Tom

      As would a 20 round magspray at or near point blank range in those “Oh sh*t!” moments.

    • PK

      The same can be said about .25acp or .22lr. That’s not quite the point.

      • Justin Roney

        In a way it is. A statistic I saw long ago said .22lr was one of the most commonly used calibers in homicides simply because of its widespread availability (don’t laugh!) I have no idea if that still holds today, but from everything I’ve read the order of importance in a gun fight still goes 1. Hit probability 2. Shot placement 3. Caliber and bullet selection. A higher percentage hit ratio (as Major Tom said) is really what the PDW was designed for, right? I just think we sometimes get caught up in the weeds and forget that catching any lead is hazardous to your health, and all small arms design involves compromise to meet the desired role.

        • VanDiemensLand

          I know that I don’t want to be shot with anything! I don’t even want to have rocks thrown at me.

          • Russ Kell

            ^ This.

            Several friends who scoff at 22. None of them will let me shoot them though. Funny that.

          • Rob

            This is a worthless statement.

            I bet you wouldn’t let someone piss on you, yet I doubt it would stop you in a fight to survive.

          • Russ Kell

            Hey, Rob. Can I piss on you? 😉

          • valorius

            so you’re saying a center mass burst of 4.6mm wont stop someone attacking you?

      • valorius

        No, it really can’t. Even the weakest 4.6mm is much stronger than even the strongest .22LR- a round that has killed tens of thousands over the decades.

    • CommonSense23

      Unless it hits spine or heart not really. I know quite a few people who have shot guys with the 4.6 and they all say the same thing. Unless you pull a head shot expect to put 20 rounds in a guys chest.

      • Justin Roney

        Do you know what distance they were engaging their targets? Just curious. And are you talking about putting enough rounds in a target to get them to stop fighting or cease their life functions? It doesn’t surprise me it takes a lot of rounds, after all it’s a relatively small cartridge designed for high volume automatic fire with a compact weapon. Again, trade offs.

        • valorius

          I saw a BIG dude go down from ONE hit to his thigh from a .22 once.

          I think tough guys talk a lot of nonsense.

          • zeitgeist

            Actually, when I was working as a PSD contractor in Iraq, Afghanistan, and later in Northern Mexico, other teams in my area used MP7’s. They were easy to conceal at meetings, and loud for breaking ambushes, but that was it. The consensus was that the magazine held enough rounds to properly service two targets. In a case like this, a hit that kills them 5 mins later might as well not have happened, so, yes, these tiny bullets required a long burst to be quickly effective.
            In Mexico we were issued P90’s. Everyone loved them. Well made, reliable and easy to carry and use, but after two contacts where the rounds demonstrated that they just could not penetrate even light cover reliably and were not terribly effective when they hit meat we replaced them with 10″ M4s and MP5s.
            I was in New Orleans 24hrs after Katrina, and saw the Homeland Security types with their P90s come through and each one of them said they’d rather have their MP5s back. I’ve spoken to people from a dozen agencies and organizations that use/used these two calibers, and the only ones who have ever had anything positive to say were those who have never had to shoot anyone with them.
            Dismiss me as an internet tough guy if you’d like, but your .22 comment tells me you’ve never been downrange. If you had, you’d have seen small/medium sized guys take 3 solid 556 hits and get found dead after running a mile, or in a hut dying of an infection 2 weeks later. If the .22 stopped your BIG dude, it’s only because he wasn’t really wanting to fight.

          • valorius

            I was in the US Army infantry. I also spent almost 20 years working the streets of killadelphia and Camden (where i saw far, far more violence and craziness)
            as a repossessor and investigator in neighborhoods that are, frankly,
            far more dangerous than the duty many “downrange” soldiers will ever see
            in their lives, including many combat arms types. I’ve been ran over
            three times on the job, stabbed, and shot at, because inner city
            sociopaths thought a long prison sentence was preferable to turning over
            the car they weren’t paying for.

            I’ve seen very large, angry tough guys stopped with pepper spray, let alone a center mass hit from 5.7mm or 4.6mm.

            We had a guy break into my old man’s rental who proceeded to STAB HIMSELF
            repeatedly in front of the terrified family that rented the place, and
            had to be repeatedly tazed, then soak up a dozen rounds of .45 HST from
            Philly PD to finally be stopped.

            On the flip side of the coin, we have a young, strong, rage filled felon 6’2″ felon like get
            instantly stopped from a single round of 9mm to the chest in a fairly recent infamous national event.

            Most people don’t “really want to fight”, or they wouldn’t go down from tiny
            grenade and artillery fragments, which are what cause the overwhelming
            majority of casualties in wars. I ABSOLUTELY concur the will to fight is
            the over-riding factor in what stops someone, but people who “really
            want to fight” are known to take 12ga slugs and keep fighting. You come
            up against one of them, and it really doesn’t matter what you’re using,
            does it? Most people want to live, so any hit of almost any kind will
            put them out of the fight. What’s more, there is a hell of a large stack
            of bodies in this world that were put in their graves from .22LR,
            .32acp, and similar very underpowered rounds.

            And if medium guys
            are taking 3 hits of 5.56mm center mass, then the criticism that it
            takes multiple hits from 5.7mm or 4.6mm to stop a bad guy are quite
            meaningless, aren’t they?

            I think the over-riding determining
            factor in what works, after will to fight, is bullet design. I’ll be the
            first to tell you that the military SS190AP round is far less than
            ideal for causing rapidly incapacitating rounds..but they do a heck of a
            lot more damage than a tiny grenade or arty fragment does. In any case,
            this is why i opted for Elite S4M, which both tumbles and
            sheds/fragments it’s jacket, while still achieving 12″ penetration in
            gel.

            It is my opinion, based on 20 years of seeing absolutely
            crazy stuff on the streets of Philly and Camden, that what you’re using
            is really of very little importance at all, and we internet gun people
            worry way too much about this stuff.

            Like i’ve said, i’ve seen a
            big violent felon quelled by a .22 to the thigh, and i’ve also seen a
            105lb female stalker take an entire 4 oz can of LE CS/pepper spray to
            the face and then sit there calmly for 40 minutes til the police showed
            up, before leading them on a high speed chase, and require 4 male cops
            to finally subdue her.

            You can worry about “this caliber isn’t
            enough,” but my “downrange” experience tells me that caliber is of very,
            very little importance. Bullet design, if anything, is far more
            important.So that’s where i’m coming from.

        • CommonSense23

          Arms length to 75 meters. The thing to understand how the MP7 has been used in Afghansitan a lot is a replacement for the MP5SD. The MP7 with suppressor is incredibly quiet thanks to the giant can it has on it. So it become popular due to the fact the guys using it often 75th guys pulling security with 240s and such so it would leave the assaulters with only having to worry about close range, and plenty of ISR/CAS support. So guys with the MP7 weren’t that worried about needing to shoot past 100 meters. Problem with the MP5SD is the round is leaving the barrel subsonic and already dropping like a rock. Trying to pull a CNS headshot off is actually pretty difficult. So having a gun that is having a much flatter ballistic flight makes it far easier to make those hits at a unknown distance with a laser at night. It’s also why the 300BLk had kinda relegated the MP7 to trash ops. A gun you get the best of both worlds with a capable caliber.
          And getting them to stop fighting and cease life functions should be viewed as the same thing. If a guy wants to fight to the death they will fight until either a CNS hit prevents them from doing so or unconscious from blood loss. Having to wait 10 minutes to death cause of blood loss is not something you want your round.

      • valorius

        several huh?

        I call wildly blatant bs.

  • The Liberty “National Defense” 4.6×30 is by far the most interesting version – it’s a scaled down version of the M855A1:

    “The 4.6mm is a copper/steel, 3- piece, enhanced performance, lead-free round
     Weight is 26 gr.
     The velocity is >2,550 FPS
     The ballistic coefficient is >.15
     The 4.6mm will fragment up to 9 pieces in soft tissue
     Terminal effect is >2 1/2″W x 12″ D”

    I would very much like to see this same projectile adopted for the 5.7×28, as it would greatly increase the reliability of the round.

    Overall, I believe the PDW calibers have suffered a poor reputation due to projectile design rather than power. In the case of the 5.7×28 SS190, it’s a nearly identical projectile to the M855 ‘green tip’ except with a aluminum instead of lead base. The M855 had a reputation for inconsistent wounding due to the “Fleet Yaw effect,” and the same effect is almost certainly responsible for the inconsistent results achieved with the 5.7 SS190 load.

    With a “SS190A1” load similar to the M855A1, but with an Aluminum base, the round would likely be very nasty, especially if it was loaded to the full 50kpsi that it is capable of.

    • The Liberty 4.6mm does have similar construction to M855A1, but I would like to make it clear that Liberty didn’t have any involvement in the EPR program and so in a technical sense the 4.6mm ND is not a “scaled down M855A1”. It’s a similar kind of bullet developed by a different organization.

      My reservations about it are that it won’t have much fragmentation mass, nor will it have much energy after armor penetration. I wonder if in practice it performs any better than HK’s DM11 Ultimate Combat bullet…

      I am also skeptical of their ballistic gel results, or at least how they are interpreting them.

      • ostiariusalpha

        Definitely need independent testing when it comes to anything from Liberty.

    • valorius

      Elite S4M is going to give the closest results as the round you’re describing in 5.7mm…probably.

    • valorius

      I used to keep 30rd mags in my Five Seven. Loaded to 27rds they are completely reliable. (Over 27rds the follower crosses the seam between the mag body and the extension, and can hang up when firing).

      I kept it loaded with Elite S4M, which exceeds 2400fps from the five seven pistol, and makes about 430 fpe of energy. Recoil is about the same as cheap 9mm range ammo in a M9 sized pistol.

  • tommytomaso

    My take on these two rounds, thier pistol rounds in sub guns… the last true PDW round was the .30 carbine round. Otherwise both weapons systems could of used 7.62×25 with better results if not lower round count per mag…..

    • An MP7 in 7.5FK would be pretty cool. Basically 30 carbine velocity out of a 6″ barrel, in a cartridge short enough to fit inside of the pistol grip.

      • Peter (BE)

        VZ26 and be done with it 😉

    • valorius

      Show me a pistol round that will hit 3100fps from a 16″ barrel- because there are 5.7mm rounds that do.

      • Tomaso

        That’s one part of the equation but even at 3000fps it only has mid to low 500 fp energy. ..where the 30 carbine out of 16″ has around high 700fp energy.

        And since we are talking PDW barrels will be shorter.

        • valorius

          Actually Elite S4M hits 600 fpe right on the button at 3100fps (597.6 to be exact). The same round from a five seven pistol hits 2400 fps for aprox 360fpe of energy, which is comparable to 9mm+P ammo from most major US manufacturers.

          From the P90, going from memory (Elite isn’t listing it anywhere on its site that i could find in a quick search), velocity is in the 2700+ fps range- which is about 450of energy, matching hot 9mm+P+ ammo from a service length pistol.

          .30 carbine has more energy of course, but lacks the tumbling and jacket shredding tendency that S4m demonstrates. (videos of this are on you tube). The .30 carbine FMJ bullet is a pin-hole maker. That round really needs soft point or HP ammunition to shine.

          They’re both good caibers though, IMO.

  • Padmmegh Ambrela

    How about Russian 9mm ammo 9X19(7N21, 7N31), 9X21(7N28/SP-11,7N29/SP-10) and 5.45X17(7N7 MPTs) ????????

  • Bub

    Nathaniel, wasn’t the ps90 in 5.7 one of the guns in your and Alex’s video about fun guns, but guns the serve little useful purpose or are somewhat impractical? These small rounds seem to have a love hate following.

    • ostiariusalpha

      I think Nate and Alex’ point there would be that all semi-auto SMGs are not as practical versus their full auto brethren, or compared to semi-autos with intermediate calibers.

      • Bjørn Vermo

        The whole case for a PDW is that you only carry it if you’re NOT expected to get into combat with it. You drive your vehicle, tend to your crew operated weapon, or plot on your situation map in your staff tent, but if the enemy unexpectedly gets within 100m you have something to stop him with. Large magazine capacity is important, easy reloading is not really an issue.

        • ostiariusalpha

          That’s all true, but Bub’s comment was in regard to Nate & Alex’ opinion on the semi-automatic, civilian version of the P90.

          • valorius

            my old man has an SBR’d PS90, it’s a tremendous home defense weapon, IMO.

      • valorius

        P90s and MP7’s are not SMG’s.

        • ostiariusalpha

          Yes, they are. Both HK and FN are quite clear that they are submachine guns.

          • valorius

            SMG’s fire pistol cartridges.

          • ostiariusalpha

            Both the 5.7 and 4.6 are pistol cartridges, they just have bottle-necked cases. Wherever did you get the idea that they aren’t pistol rounds?

          • valorius

            How about based on the fact that there is no production pistol on earth that fires the 4.6mm cartridge? Or the fact that the only pistol that fires the 5.7mm has a grip circumference far too large for many people’s hands (There are a couple .30 carbine pistols – is .30 carbine a pistol round? Is the M1 carbine a SMG?- no). Or the fact that the P90 came before the Five Seven?

            They are PDW calibers, not pistol calibers.

          • ostiariusalpha

            That the UCP failed to reach production doesn’t requalify the 4.6x30mm as something other than what it is, a pistol round intended for use in a pistol and SMG. And grip size is irrelevant, that would magically disqualify the M9 as a pistol. Don’t get me wrong, the Five-seveN is a thick pistol as a double stack, but .45 ACP is worse in a staggered mag; you aren’t going to say .45 ACP isn’t a pistol round because of that, are you? By the way, plenty of people that know what they’re talking about do consider the .30 Carbine to be a type of magnum pistol round.

          • valorius

            The UMP came after the MP7, as is the case with the Five SeveN and the P90. Both rounds were specifically designed for PDW’s- the MP7 and the P90. Both weapons were specifically designed to bridge the gap between pistols and assault rifles. Both weapons do things an SMG doesn’t do.

            But whatever, arguing over semantics gets real old after a while.

          • ostiariusalpha

            Both 4.6x30mm and 5.7x28mm were created to fulfill the criteria of NATO document AC/225-D/296 which specifies the creation of a pistol and submachine gun system using interchangeable armor-piercing ammunition. They were pistol rounds right from the start.

          • valorius

            PDW’s are not SMG’s, regardless of what someone’s marketing department says.

            Sorry man.

          • ostiariusalpha

            Well, since that designation comes from their engineering departments, and you have zero authority in deciding what they are, I’ll take their word for it instead. Is that’s okay with you?

          • valorius

            OK bud, PDW is not a term, it doesn’t mean anything, and words are meaningless.

            Feel better?

            A PDW fires an intermediate cartridge (again with that phrase :D) that bridges the gap between pistol and assault rifle. It has far greater effective range than an SMG, and far better armor penetration than an SMG. It is NOT a SMG, it will never be a SMG.

          • ostiariusalpha

            Both .45 ACP and 9x19mm are designated as PDW rounds by the US military. I don’t think you are familiar with the history of that term, and what it has actually meant. There’s nothing particularly special about labeling something as PDW.

          • valorius

            The .45acp and 9mm were both adopted as pistol cartridges for pistols (The M1911 and M9/M10). Of course the US govt calls M4’s PDW’s, for political reasons.

            But hey, if it’ll make you feel better, you’re right. 😉

          • ostiariusalpha

            Thanks, I am right! The US calls any weapon a PDW if it is intended for use by those troops not considered combat personnel. If the brass thought that rear-echelon troops should carry sawed-off shotguns, then those would be PDWs; politics has nothing to do with it. The M1911A1 and M9 have both been classified as a PDW when they were issued to pilots and truck-drivers. Are you understanding any of this?

  • JustAHologram

    This just reminds me of the temper tantrum that Germany threw when HK lost. If it wasn’t for that we could have cheaper surplus 5.7x28mm ammo

  • Sasquatch

    Why not use 5.56 NATO as the ode round….. Don’t get me wrong 4.6 HK and 5.7 FN are some cool rounds. I just think that 5.56 would suffice.

    • Xtorin O’hern

      5.56 guns have to be substantially bigger

      • Sasquatch

        The have some small m4s. Plus I think that a smal petite bullpup is achievable in 5.56.

        • Xtorin O’hern

          the smallest M4 is still bigger then the smallest MP7

          • ostiariusalpha

            And has the increased recoil to go with it.

          • iksnilol

            I think an Mk18 or whatever the super short M4s are called recoils more than an MP7

          • ostiariusalpha

            That was my point.

          • CommonSense23

            Unless you are shooting one handed the MK18 recoil is extremely controllable. While a MP7 is practically nothing the difference isn’t going to make up for its multiple weakpoints.

          • Sasquatch

            True but if that’s the case just take a full auto glock in 357 Sig with a fold out stock and foregrip. I just think there could be a firearm design that can shoot 5.56 and still be small enough.

          • ostiariusalpha

            There are plenty of people in the US military command structure that would agree with you, the Mk 18 has plenty of strong points over any PDW, right along with its weak points.

          • valorius

            .357 sig is not comparable to Five Seven or 4.6mm, even 9mm ball has 30% more recoil than SS190 5.7mm ammo.

        • valorius

          The small M4s are quite useless in full auto for the average trained soldier. A P90 is completely controllable full auto.

          • Sasquatch

            You’ve have shot both in full auto?

          • valorius

            Yep.

    • Chipsa

      Can’t fit a 5.56 in a pistol grip. One of the requirements was a service pistol to fire the same round.

      • Sasquatch

        Well if that’s the requirement then just stick to a hot 9mm or Sig 357.

        • ostiariusalpha

          Those rounds have drawbacks compared to 5.7 and 4.6 in magazine capacity, and recoil (with the increased effort to reacquire the target that goes with that). Also, wear on parts is lessened with the smaller caliber rounds, which is relevant to military logistics.

        • valorius

          9mm ball has 30% more recoil than SS190, wont penetrate armor, and the ammo weighs 40% more.

      • Sasquatch
      • Mazryonh

        It’s interesting to see what gun designers have managed to fit into a pistol grip. The South African MAG-7 shotgun actually managed to feed 12-gauge shotgun shells into its pistol grip, but those were shortened versions that were 60mm long instead of the usual 70mm long shells.

    • The PDW is designed to replace 9mm pistols and 9mm SMG’s – it is not in any way designed to replace 5.56.

      The goal is a round that can be fired out of a handgun or small SMG that a) can pierce Kevlar helmets and vests b) produces equal or better wounding to 9mm FMJ c) holds more rounds then 9mm magazines of the same length.

      With the right projectile, 5.7 and 4.6 meet these goals, with 1/3 the recoil and 1/2 the cartridge weight when compared to 9mm FMJ.

      • Sasquatch

        I realize this but when I think pdw I think small gun not handgun. I can see the advancement for a handgun round but for replacing a smg I don’t. I just think that there could be smaller firearms that can soot 5.56. The Sig mcx seem close just turn it into a bullpup and bam.

        • valorius

          the small PDW weapon such as the P90 was intended to replace handguns altogether.

          • Not exactly. The NATO requirement was for 2 “PDW’s” – a “handheld weapon” that weighed less then 2.2lbs that held at least 20rds, and a “shoulder weapon” that weighed less then 6.6 pounds and held 20rds+.

            In order to qualify as a PDW round, it had to be able to be fired out of a handgun.

          • valorius

            That disqualifies the 4.6mm round right off the bat. The Five Seven would fit the bill, but it’s grip is way too big for general issue to female (and indeed many male) soldiers.

  • Gambler X

    Didnt H&K design a pistol to go with the MP7? Whatever happened to that?

    • They were unable to make the 4.6 deliver enough performance out of a handgun length barrel; in general, the narrower the barrel, the longer is has to be to reach optimal velocity.

      • Gambler X

        thanks. i saw a picture of it in Shotgun News so long ago when the 5.7/4.6 hype was starting then not another word.

    • valorius

      cancelled- excessive barrel erosion, IIRC.

  • 40mmCattleDog

    Just had to remind me of my unatainable dream of buying a civie MP7 didnt you.

  • Rimfire

    Just happy that I am not the ammo dealer for all these specialty rounds, how does one keep up and still manage inventory?? Around here still seeing unopened boxes of WSSM in various calibers too.

  • valorius

    Ah yes, the round that killed the 5.7mm pdw with NATO cause the germans threw a hissy fit when they lost.

  • Openmindednotangry

    Boy is it a HOOT to shoot!

  • roguetechie

    Nathaniel,

    It’s funny that you mentioned a sabot 5.7 load WRT armor penetrating ability.

    This, among many other factors, is what drives my fascination with and preparation for experimental work with the 7mm Penna and other loadings that utilize 5.7×28 brass. Including eventual experiments with sabots and sabot like objects that extend rearwards of the case mouth, potentially all the way to the case shoulder and at up to full case diameter at that point.

    This relates to some of the AP loads Van bruane Rik experimented with that were meant to work within the chamber designs and pressure limits of existing pistol rounds like 9×19 .40 10mm etc.

    Van Bruane Rik is a genius, and the utter lack of support / acceptance of his work in the west is a tragic missed opportunity.

    One more data point to add to the mountains of evidence that conventional firearms and ammunition technology in the west is stagnant, rather than a mature technology rapidly approaching the point of diminishing returns on new development as so many try to insist.

  • Giolli Joker

    I wonder if anybody has ever converted a Five-seveN to fire 4.6×30…
    It would be a cool comparison platform.

  • Evil_Bonsai

    I know there’s still more rounds to discuss, but based on pistol grip magazine size, energy delivered, recoil, et al, would there be an ‘ideal’ pdw round? I’ve been thinking of such a beast, and though I haven’t really compared anything, I was thinking something along the lines of 5.7×28 OAL (or close enough, to fit in a pistol grip in a medium sized hand), somewhere between 9mm-.45ACP diameter case, with a 6-7mm caliber, maybe something about 80-95 gr.

    • The 7.5 FK shoots a 100gr bullet at 2,000fps out of a 6″ barrel, for 888ft/lbs of energy.

      Out of a MP7 style weapon, it would likely prove to be the “ultimate” PDW round.

  • Jay Wolf

    Not really. The 4.6 came out the same time as the 5.7 from the same NATO program. It is only available in one platform, a full auto PDW, and it is only used in one country Germany. The P90 is used by hundreds of military and LEO units world wide.

    • CommonSense23

      The US military uses the MP7.

  • Justin Roney

    Fair enough, I believe I found the DOJ paper you got that from and read through it a bit, the most striking thing about that list is that most are basically 9mm/.38 or smaller. I believe this still points to availability being the biggest factor.

  • Mazryonh

    Was the 4.6x30mm cartridge partly inspired by the earlier 4.73x33mm caseless cartridge from H&K’s earlier experience with the G11 rifle? The 4.73mm diameter projectiles used by the G11’s ammunition should have been similar to those used for the MP7’s ammunition, since they have similar diameters and are spitzer-tip bullets.

    • ArjunaKunti

      It was mainly inspired by the HK/Cetme 4.6×36 spoon tip cartridge from the late ’60s and ’70s. The 4.6x30mm cartridge has the same bullet caliber and length but shorter & thinner case in order to fit to PDW type weapons.

      • Mazryonh

        I see, I thought that since the 4.73x33mm cartridge was younger the know-how that went into that cartridge would have gone into the 4.6x30mm as well. But in any case it seems that this family of calibers needs multiple hits for rapid incapacitation, which was accomplished with the G11’s 1800 RPM three-round-burst feature.

  • Miguel Raton

    Just run a reinforced 22CCM case at the 5.7x28FN pressures & be done with it already. Might have to put a roller-lock or something into your PMR30 to keep it safe tho’, but conversion to centerfire for that platform should otherwise be a trivial matter. Problem solved, now where can I pick up my royalty check? 😉

  • valorius

    The only documented real world results we know of for 5.7mm is the Fort Hood shooting.

    When the terrorist attacked initially, 2 soldiers and an orderly attacked him immediately (One soldier threw a table, while the orderly and the other soldier charged him) All 3 were stopped instantly by weak SS197 V-max rounds from a five seven pistol.

    These were 3 grown men full of adrenaline, attacking at nearly muzzle contact range- all three were immediately stopped by 5.7mm SS197 v-max rounds.

    The next phase of the attack was against non resisting defenseless individuals, so is of no relevance.

    In the final phase, when the cops came, one cop was put down immediately by an SS197 to the knee, which shattered her knee in dozens of pieces (putting her on permanent disability, and requiring her to have numerous reconstructive knee surgeries) The terrorist walked up and disarmed her. When her partner engaged him, the terrorists five seven jammed, but it took FIVE SHOTS of police JHP to stop him.

    So in the one well documented incident we have to go by, when faced with 5 determined attackers, the terrorist stopped four instantly with “weak’ FN SS-197 V-max, and was only finally stopped by the second cop (officer Todd) because his gun jammed. Noting, that again, it took five rounds of 9mm JHP to stop the terrorist, including a spinal hit.

    To me, a five seven will work on any person that any gun would reasonably be expected to work on, and would fail just as spectacularly as any other gun when you face one of the “Im gonna fight you to my dying breath” type of guys.

  • valorius

    According to G3Kurz over at hkpro, the MP7 is still in use by SOCOM forces as an entry tool. G3Kurz is the career HK employee who gave us the HK Grey room. He’s not just some “internet guy.”

    PS: There are very few places in Iraq or even Afghanistan that are more dangerous than Camden. Just sayin’. With all honesty, parts of Camden belong in Somalia, not the United States.

    That place is flat out crazy.

  • valorius

    BTW, thanks for your service.