What we call a submachine gun, the Germans call a “Machine Pistol”. Hard to imagine the Thompson gun being called a “pistol” but it makes more sense for weapons like the MAC-10.
Sub-machine guns fire pistol rounds. Machine guns fire rifle rounds. Oh, and .22 is considered a pistol round. The US Carbine M-2 fired .30 caliber pistol rounds. They were hot for a pistol round, and I don’t think anyone made a pistol that would shoot them, but there you go. Out of the box, they’d fire 4" groups at 100 yards, which is lousy compared to a Main Battle Rifle (like the M-1 Garand), but the carbines were introduced as replacements for the M-1911a1 .45 Colt auto pistol, which wasn’t much good over 40 yards.
Sub-machine guns fire from removable magazines and from the shoulder or hip. Machine guns fire from belts or large canisters from a tripod, bipod, or a pintle mount and if they’re not mounted on a vehicle, they require a crew to shoot them.
Then there’s the BAR. Full auto, full sized round, loaded from a magazine, and fired from a bipod unless you were a football lineman. It really didn’t need a crew to operate it, but a private following the BAR guy around loaded down with charged magazines was useful. I guess at first it was considered a Light Machine Gun (LMG) but in my time, it would be a Squad Automatic Weapon (SAW). When the M-14 was introduced after the Korean War, it was supposed to serve as either a MBR or a SAW. All it took was a minor change of a part or 3 at the lowest Ordnance depot level to make the conversion for full auto. The problem was, the M-14 was much lighter than a BAR and turned out to be virtually uncontrollable at full auto.
And referring to what** Lumpy** just wrote, it might have been more accurate for them to call the Thompson a “Full Auto Carbine”, but that never happened.
I wouldn’t say that all SMGs shoot pistol rounds, exactly; the Uzi 9mm round may be the exact same size as a regular 9mm round, but it has a bit more of a charge. At least, I was taught never to use Uzi rounds in pistols (although that might have been a tall tale designed to prevent ammo theft).
Note that the FN-MAG (or M-240, as the U.S. calls it), one of the most popular machine guns of the past 50 years, is basically the BAR turned upside-down, beefed up and adapted to belt ammo.
It’s 9mm Parabellum just the same. Perhaps +P or +P+ (more powder and pressure than usual). Still safely usable in some pistols but it’s simpler for the military to just have a blanket rule prohibiting its use in all pistols.
From the M1 Garand owners peanut gallery:
Who says the Garand is not effective up close because it is large and heavy. Just whack ‘em in the head.
:dubious:
My understanding is that full-auto weapons use a blowback/ gas operated mechanism that requires more power than the simple recoil of semi-auto handguns. As mentioned upthread, a semi-auto pistol designed to take the pressure could use them.
In a previous life, I was trained on the M-48 tank. The crew were given 45 Cal pistols and what they called a burp gun. It was a light weight rapid fire weapon. I don’t remember the caliber. They told us it used the gas from the round to power the mechanism. It had a burp like sound when fired. I remember they taught us to use it sideways, because if it was handled vertical it tended to ride up.
They did make 7.62x25mm rounds, mostly Czechoslovakian I think, that were intended for (sub) machine guns and not recommended for pistols*.
Blowback, gas piston, direct impingement, a few more I think. Blowback is common in smaller-caliber pistols, or recoil in larger (most 9mm or larger are recoil, while the slightly smaller 9x18mm and .380 are blowback).
*ETA: Or rather maybe just pistols designed for them, see this.
Perhaps you’re referring to the M3 Submachine Gun, aka “grease gun”? It was cheaper and easier to produce than a Thompson, but still fired the same .45 acp round.
Yeah, that is it Ranger Jeff. It was a lot of fun to shoot. And had an unique sound. Gracias!
I believe the saying is “one dead, one injured”. 
I wonder what the muzzle flash is like with that beast.
What does 1D6 in the comment mean? Ie, I don’t get the joke.
It’s a role playing game indicator of damage you’ve received.
“Role playing game” is an industry-wide (electronic) game genre, with common ratings?
The last computer game with graphics I played was Pong, when it first came out. Later at work I played the text game Zork. I think. The one that started with a door…?
Gangsta!
Isn’t that way of holding the weapon ridiculed for the inaccuracy of fire?
[When did that become an affectation of gangsta, anyway?]
1d6 is paper and dice style role-playing-game shorthand. It means one six-sided die roll (or in other words, one to six points of damage). It’s basically saying you’ll do some significant damage to yourself every time you shoot it at someone else.
It’s basically XdY where X is the number of dice to roll and Y is the number of sides on the dice. 2d6 would be two six-sided die rolls added together. 2d8 would be two eight-sided die rolls added together. RPG games play with all kinds of funny sided dice.
Lots of .500 S&W photos out there, but the one I like best is from the Halloween episode of the TV series “Bones”: http://www.imfdb.org/images/2/28/Bones_31.jpg
Sure it’s inaccurate; but if you’re trying to sweep gunfire over a bunch of people, the muzzle climb works with you that way. The basic purpose of full-auto fire is “if you don’t hit one target you’ll hit one of the others”.