A Thompson M1A1 is classified as a submachine gun even though it is the size of an M4 assault rifle. Why?

Question

My friend asked me this question and i never noticed it before, but it's true.

Answer 1

Because it has nothing to do with size of the gun. Thompson sub-machine guns (like all sub-machine guns) fire pistol ammunition (.45) rather than full size rifle ammunition.

Answer 2

The Thompson, especially the early Model of 1921, has a fairly high rate of fire 900+rpm, higher than many other submachine guns of smaller caliber. This rate of fire, combined with a rather heavy trigger pull and a stock with excessive drop, increases the tendency of the gun to climb off target in automatic fire.

Compared to modern 9mm submachine guns such as the Uzi, the .45 Thompson is heavy, difficult to aim and has excessive recoil. By the standards of the day, however, the Thompson was one of the most effective and reliable submachine guns available.

Answer 3

I actually have responded this very similar question various circumstances, i do not recognize why human beings repost it, yet any way... It has no longer something to do with length or weight. that is about the dimensions of cartridge it fires. Sub-gadget guns hearth *pistol* rounds in both semi-computerized, totally-computerized or burst hearth modes. attack Rifles hearth intermediate *rifle* rounds in both semi-computerized, totally-computerized or burst hearth modes. The Thompson fires a .45acp cartridge, a pistol round, making it a sub-gadget gun. The M4 fires the 5.fifty six cartridge, a rifle round, making it an attack rifle. There are conversion kits for M4s that adjust it from 5.fifty six to 9mm. that is an analogous rifle, similar weight, similar length, although the diverse calibers make one an attack rifle (the 5.fifty six version) and the different a sub-gadget gun (the 9mm).

Answer 4

Thompson fires .45 ACP, same as the venerable 1911 a pistol round. General Thompson that designed the Thompson came up with the catagory. The M-4 fires a rifle round.

Answer 5

And it's a hell of a lot heavier than an M4 as well. It's considered a SMG because it fires pistol ammunition rather than a rifle round.

Brian, whether a weapon fires from an open or closed bolt has nothing to do with any nomenclature except open or closed bolt. And for the record, the Thompson SMG fires from an OPEN bolt, not closed.

John, the term has nothing to do with a subsonic round. Yes, the .45ACP in the standard 230 grain load is subsonic in the typical 5" pistol barrel (and I believe remains subsonic in the Thompson's ~10" barrel), but ANY 9x19mm SMG with standard velocity ammo (such as the MP5 you use as an example) will produce supersonic velocities.

Answer 6

The ammunition used separates a submachine gun and an assault rifle. Submachine guns fire pistol rounds, just at higher rate of speed, such as a 9mm or .45 round, .45 in this case. Assault rifles fire larger rounds, such as a 5.56x45mm or 7.62x39mm. An M4 is the carbine counterpart of the M16 assault rifle.
http://en.wikipedia.org/wiki/Image:Many_bullets.jpg

Answer 7

As others have said its not the size of the rifle, its the round that it fired. Yet I have seen no answer that is correct. The sub in submachine gun refers to the speed the round travels, ie Feet Per Second. The .45 is a subsonic round, the .223 and 5.6 and 7.62 of the later M14/15/16 and AK are supersonic rounds.

Typically a submachine gun is an automatic rifle firing a pistol round. The HK MP5 is another good example as it fires a 9mm pistol round.

Answer 8

Id say b/c it shoots a 45ACP round ..... assault rifles shoot a round batween a full rifle round and a pistol round like a 223. for m4,or 7.62x39 for ak47

Answer 9

this is because the thompson fires a pistol bullet.

The M4 is a carbine(short rifle).

Answer 10

Others answers on here are correct, but only partially. One significant part defining a machinegun from a submachinegun is the way the ammo is fed into the firearm. All the Thompsons, MP5s, UZIs, and others all fire from a standard magazine like a rifle or pistol. Whether it's staggered or straight stacked ammo, it still comes from a box shaped magazine. And all these submachineguns also fire from a closed bolt.....meaning the round fires and then the bolt cycles back and forth to reload. On a 'real' machinegun, the ammo fed into the rifle is belted ammo, or all the rounds are linked together and feed in from the side. Also, machineguns fire from an open bolt, meaning the bolt is in the rear position and chambers then fires a round after you pull the trigger, then returns to an open position after you stop firing. It works this way because of the linked ammo.