The M2 Carbine: Assault Rifle or Submachine Gun?

The M2 Carbine was a mechanically simple modification of the M1 Carbine to allow fully automatic fire. The fire prototypes of the M1 Carbine had actually been selective-fire guns, but that requirement had been dropped by the time the Winchester design was officially adopted as the M1. It was a feature quickly requested by troops once the Carbine entered active service, though.

In 1944 the US Army acknowledged this, and introduced the M2. A total of 217,000 were manufactured at the end of WW2, and did see limited service on Okinawa – and then extensive use in the Korean War and Vietnam War.

The M1 Carbine has long generated controversy among those attempting to rigidly define its role, as it falls awkwardly between the notion of submachine gun and assault rifle, firing a cartridge that is clearly more powerful than a pistol round but equally clearly less powerful than an intermediate rifle round. Its originally intended role was as a personal defense weapon more effective than the 1911 pistol, and in service it always scored high marks for handiness and poor marks for combat effectiveness. The opinion of soldiers using the Carbine in either its M1 or M2 form was very much dependent on what role they expected it to serve.

In my opinion, its light weight and stock design make it a sub-optimal submachine gun, and its light cartridge makes it a sub-optimal assault rifle. But if you need a light and handy carbine to carry a lot and only use in emergencies, it is hard to beat for its time.


      • It was actually developed to be as what now be PDW – weapon for drivers, artillery crews etc. (bud ended up being issued widely among the forces as primary fighting firearm). It also falls into Assault rifle category by being between SMG and rifles, althru the cartridge is underpowered compared to contemporal 8mm kurz or later 7.62×39.

        • On the other hand, compared to post-WW2 PDWs the M1/M2 Carbine also fires a very powerful cartridge. The PM-63 and Škorpion fired pistol cartridges, and the P-90 and MP7 fire small caliber bottlenecked cartridges, essentially downscaled assault rifle cartridges, but all of them are considerably less powerful than the .30 Carbine.

          • And now 9×30 мм ГРОМ cartridge:
            isn’t it similar to .30 Carbine? However main reason for creating this cartridge was to make “armor-piercing” sub-machine gun, that is one able to go through bulletproof vests. Known loadings:
            FMJ: 6,42-6,55 g bullet @ 600-610 m/s (from «Гепард» sub-machine gun)
            AP: 6,70-6,74 g bullet @ 590-600 m/s (from «Гепард» sub-machine gun)

          • Daweo,
            There were also experiments in Finland with a long 9mm intermediate round, called the 9mm Lilja, with modified Suomi SMGs as the test bed.

            Beyond that, I don’t know anything about it. Might it and the Soviet experiments have been with the same Cartridge?

            Also, i wonder which side of the frontier, the experiments began?

  1. Based on the high speed video, I take it that that particular magazine had a kind of bolt hold-open feature stamped into the follower as well?

    Also, clamp-on muzzle breaks were made for it, and do a pretty good job of controlling muzzle climb and recoil impulse.

  2. I’ve long had an opinion that the big problem with the M-2 (which I’ve never shot) is based on my experience with the M-1 which I do have a lot of. Basically, based on both my own experience and what I’ve heard and read: the 15 round magazines are rock-solid reliable and the 30-round “banana clips” are a bit quirky, to put it charitably. Obviously, a full-auto weapon limited to 15 rounds has limited appeal, and a 30-round weapon with a tendency to jam has even less.

      • Someone decided 20 rounds is enough – the fact that the rifle started its life as semiauto probably contributed to this. Even when M16 was introduced, 20 rounds seemed enough to the pentagon. When american soldiers in NAM encountered AK-47’s, they quickly demanded thirtyrounder magazines.

        • In fact, the very earliest Armalite aluminum magazines were designed to hold 15 rounds because the Carbine box magazine held 15 rounds. Then somebody at Army Ordnance discovered that you could jam 20 rounds into one, and the “20 round M-16 magazine” was (officially) born.

          The Air Force wanted more than 15 rounds, so Fairchild designed a 25-round steel magazine. Then (again) some supposedly smart guy at Ord discovered you could jam 30 rounds in one. The M-16A1 “30 round steel magazine”! Hallelujah!

          Troops in-country learned the hard way not to put more than 15 rounds in the “short” magazine (aluminum or steel) or more than 25 rounds in the “long” steel magazine.

          I have used those plus aftermarket AR magazines for a long time, and loading either one to its “official” capacity weakens the spring and causes feed failures. As long as you only use them as 15 and 25-round maximums, they work reliably.

          BTW, the 30-round “banana clip” for the M1/M2 works best with a maximum of 28 rounds in it. And never put more than 28 rounds in a Bren 30-rounder.

          PS; The SAS would gig anybody who ever put more than 10 rounds in the “13-round” FN 9mm HP magazine. I can personally confirm the wisdom of this procedure.



          • “BTW, the 30-round “banana clip” for the M1/M2 works best with a maximum of 28 rounds in it.”
            So far I know during WW2 loading not to full capacity was also used for STEN sub-machine gun.

          • The first box magazine for the M/31 Suomi SMG was designed to hold 25 rounds, but in order to make reloading by hand convenient, it had a too weak spring and didn’t actually work reliably with 25 rounds loaded. 20 rounds was fine and the official capacity was later revised to 20 rounds as well. The Swedish-designed 50 round box magazine was usually loaded with about 40 rounds. Loading to full 50 round capacity was not recommended, but 45 worked fairly well with new magazines.

            The only box magazine for the Suomi which worked reliably at almost full nominal capacity was the Swedish M45 Carl Gustaf’s magazine adopted for the Suomi in 1954. Nominal capacity was 36 rounds and it was usually loaded to 35 rounds.

      • The original 20 rounds double stack magazine had reliability issues. So a more reliable single stack magazine was designed with a reduced capacity of 12 rounds and the same external dimensions so it can fit the magazine well without modifications.

    • 15 rounds is less than ideal for an automatic weapon, but it’s still five on average 3 round bursts, so not unusable in my opinion. In WW1 the German Sturmmann soldiers with MP 18 SMGs sometimes used 8 round Luger magazines as reloads, because there were not enough of the drum magazines, they required a loading tool to load and were very unwieldy to carry.

  3. “M2 Carbine: Assault Rifle or Submachine Gun”
    I would say that it is sub-machine gun, it did not use automatic pistol cartridge, but shows traits – almost straight-walled and use round-nose bullet.
    Notice that other nation also sometime used “hot” load for their sub-machine guns not to be used in automatic pistols, but with case same as standard pistol cartridge.

  4. “In my opinion, its light weight and stock design make it a sub-optimal submachine gun, and its light cartridge makes it a sub-optimal assault rifle”
    Looking at sub-machine guns development, first appeared big-size sub-machine guns, that its with full wooden stock, much later smaller size sub-machine guns appeared (for example MAS-38), US forces decided to adopt new cartridge and weapon rather than searching lighter sub-machine gun, which might be partially caused by fact of usage .45 Auto cartridge, which was heavier (per example) than other nations automatic pistol cartridges.

  5. Similar case to M2 Carbine is Hungarian Danuvia 39M which fires 9×25 cartridge (then default Hungarian automatic pistol cartridge was 9×17) and use delayed-blow-back principle rather than pure blow-back. Later weapon similar to Danuvia 39M was made for .30 Carbine cartridge – San Cristóbal Carbine, see photos:

  6. “Personal Defense Weapon” A true category of its own with oddball calibers such as .30 Carbine and today various 4.6s and 5.7s.

    On a personal note, my late Grandfather carried a Carbine in the ETO. He said it sufficed. On another personal note, I have a nifty Carbine so someone, somewhere PLEASE make a reliable 30 round magazine!!!

    • The problem is that most gun-hating liberals will claim you’re out to commit mass murder if you need a 30-round magazine. Those nitwitted gun-haters think “We all live in a ‘picture perfect world inhabited only by perfect people’ and guns are not part of our world.”

      PDW’s also seem to be considered a novelty in that they emulate assault rifles but cannot hold a fight with them… Or am I wrong?

      • PDWs are not supposed to “hold a fight” with assault rifles… They are designed to replace the handgun as a self defense weapon for troops who can’t be expected to carry a full size assault rifle around just for the occasional need to defend themselves against enemy infantry attack.

        In my opinion a PDW should be small enough to be carried in a holster, which is why I think that the PM-63, PM-84, Škorpion and MP7 are better PDWs than the P90, which is too big to be comfortably holstered, and quite heavy as well compared to handguns. The P90 is, however, an excellent submachine gun. Just like the M2 Carbine would be have been if it had had a more reliable 30 round magazine…

        • So would a Mauser Schnellfeuer with stock-holster count as a PDW? As a pistol, the C96 handled awkwardly without the stock.

          • I suppose it would, although deploying the stock holster is a little to slow in my opinion. The Schnellfeuer also had an excessive rate of fire. The Astra 904 would be better in that regard.

          • I would like to add that the first PDW was probably the German WW1 vintage “artillery Luger”. The PDW concept has been invented many times since the beginning of the 20th century and then partially forgotten, only to resurface again couple of decades later.

      • The purpose of a PDW is to arm troops who would otherwise have a pistol, SMG or shotgun with something that is less bothersome to carry than a subgun or riot gun, but easier to actually hit something with than the pistol or SMG, plus having more practical useful range than the pistol or shotgun.

        Support troops (logistics, cooks, whatever) have things to do other than carrying and shooting firearms. If a weapon is too much aggravation to carry around in the course of their (non-combat) duties, they tend to “lose” it or at least leave it in the vehicle, etc. Which means that when they need it badly, they don’t have it.

        As Edwin Tunis observed (Weapons, 1954) the Carbine is lighter than the shotgun or SMG, thus encouraging the troops to keep it with them. It has less recoil than either one, even in full-auto on the M2 version, which also helps. And it’s overwhelmingly easier to hit with in aimed, rapid fire than any handgun, simply by being a “longarm”.

        Power-wise, its 110-grain FMJ leaves the muzzle at about 1850 F/S for 840 FPE. At 300 yards (the highest setting on its rear sight) the slug is still moving at about 1350 for 450. Meaning, at 300 it’s still delivering the same punch as a slug from a .45 or 9mm SMG does at the muzzle. At any range, it has greater penetration than any .45 or 9mm service pistol round.

        And it certainly outranges any shotgun.

        As for the cartridge not “coming up” to the power of an actual “intermediate” round, see .22 Spitfire aka 5.7 MMJ;

        Melvin M. Johnson designed the round in the late 1950s to provide a conversion of the M2 to a “true” assault rifle with ballistics matching the .223 Remington to a great extent, but in a smaller and lighter “package” than the Armalite. In most respects, it is a ballistic duplicate of the .221 Remington Fireball round for the XP-100 pistol and the original Armalite “arm gun”.

        Interestingly, both rounds ended up being remarkably similar to one that was popular around the turn of the 20th century. See 5.6 x 33 Rook;×33-rimmed-rook/br?cid=9026

        While the rimmed version (5.6 x 33R) is better known today for use in German drilling and vierling break-action rifle-shotgun combinations, the rimless version was used in some “short-action” bolt-action repeaters with box magazines.

        Either version only had a MV of around 1600 F/S with a 60-grain bullet and thus a ME of around 330 FPE, but that was due to mainly being loaded with black powder or early smokeless types. We’re not talking about a 5.6 x 61 Vom Hofe Super Express, here.

        Dimensionally, it was pretty close to the American .22 Hornet or .218 Bee, so it was smaller than the 5.7 MMJ, closer in most respects to the modern 5.7 x 28 FN P90/FiveSeven round.

        So as you see, there really is “nothing new under the sun”.



      • Ian and everyone else here are discussing the technical aspects of the M2 carbine. It’s a very interesting discussion. Hackneyed political rants are not very interesting.

        • My mistake for including politics. But back to technical items. According to some of the posts in the thread, a good PDW must be handy enough to carry on oneself (preferably holstered or slung in front for easy deployment should a hostile jump out of nearby bushes), more accurate than a pistol, and relatively user friendly. Any ideas on how a PDW should work given viable cartridges? Would we want gas operation, recoil operation, or a delayed blow-back mechanism?

        • They are a reminder of the fact one cannot take firearms ownership for granted. If you spot a rant storm coming in the first sentence you can skip that comnent. Go bury your head in nearest tech-detail dune.

  7. My father told a story from when he was in Korea when 2LTs would show up to lead patrols carrying M2s. He claimed it was inevitable that they would do a weapons check on full auto, with bayonet attached, and shoot the bayonet off the end of the weapon.

    One of the few stories of his time there he always chuckled about.

  8. Be whatever may be, I’ve heard a tale, which is so silly and non-functional that it may even be true. It has to do with a newly minted (French, or Brit, or yank, or Russ, or… well, a universal classic 2nd looey, Coronet, Subaltern, or…grossly inexperienced (very) young (perhaps accidental) officer-like type.
    This fellow arrives on the line, with his new (M2, or ppsh, or Lancaster, or Thompson, or C96/20, or… whatever…loaded and ready to go.)
    Checking in to the headquarters bunker, he perceives an invitingly convenient spike lodged in a wood support beam, clearly meant to hang his new (PDW, Pistol, SMG, AK…Whatever…)
    The results are clearly predictable.
    The weapon, equipped with the convenient, hangable circular trigger guard, immediately begins to fire…each recoil resets the mechanism an continues the festivities…
    God help us, with all those guys running out the door, jumping out windows an all and thinking, ” At least it’s on semi.”
    But still, it goes on for a real long time…
    This can go on for real long time

  9. I’ve used the M-2 quite a bit and though the one I carried was quite worn it rarely jammed and had adequate stopping power at realistic ranges. One secret is to choose your mags wisely as this is the reason for most stoppages. The M-1 was adopted as a replacement for the 19111A1 and so is a PDW, though soldiers like Audie Murphy took out a number of snipers with his at close range.

  10. If you love the carbine and have a Facebook profiles join my group on there. “M1 carbine/Garand trading”
    We have over 5900 members

  11. I think the term “machine carbine” would properly describe the M2, it is kinda hard to place where it fits. There is a lot of things it is and a lot of things it isn’t.

  12. It can’t be an “assault rifle” it’s not black, has no pistol grip (at least this one doesn’t) there’s no flash hider, it’s not covered in optics and flashlights like a real mall ninja assault rifle should be…. We never see it used by the bad guys in action movies….. It just doesn’t have that scary look that real gun experts look for when classifying rifles…..

  13. As I can see control is not an issue.
    I have a question if someone can answer it: there is (as it looks to me) an extra ballast weight on operating rod. Was it to lower rate of fire?

  14. Just a random thought, but does anybody know of, or has anybody ever heard of, an M2 in Melvin Johnson’s 5.7 cartridge?

    • I used to see one at local gun shows. The seller was asking an astronomical price, which included dies and some brass. I left home for a few years and I am almost completely certain I saw the same rifle, same seller, and same price years later.

  15. The M2 CARABINE WAS the first real machinegun/rifle I ever saw and TOUCHED
    It was in about 1966 when I was 14
    The original ELLWOOD EPPS shop in Clinton ontario now in orillia had a M2 hanging out on their public could touch gun racks
    When I went up on saturdays with my dad I used to spend at least half an hour manupulating the selecter swith and fondling the stock
    My dad wouldnt buy it as he considered the carabine cartrige useless and the gun was almost 200 dollars cdn
    This however got my interest up and when I was 16 I got him to buy a mk 111 sten it was only 60 dollars cdn and canadian made not yankee

  16. My father once told me how his favorite weapon for one of his early Vietnam tours (a staff tour where he spent a lot of time riding Hueys to various camps and firebases) was an M2 Carbine, with an M1A1 (paratrooper) stock that had been relieved to fit the M2 “go faster” bits.

    “Fold the stock, sling it behind my back, and forget about it. Even less trouble to carry all the time than an M16. Enough gun to get me away from the scene of the crash, and enough gun to ‘find’ an SKS or AK should I need one while waiting for SAR.”

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