What is the purpose of sub-machine-guns?

[DocFrench]

Having carried a pistol (M-9 or M1911), rifle (M-16, A1 & 2) and shotgun as "assigned weapon" as an Army Medic & Navy Corpsman, I would have jumped at the chance of having a short barreled, large capacity fast firing weapon that could be fired 1 handed. Saddly, it never happened. Back in mid-80's our Tank crews still carried M-3 Grease Guns. Those were fun!

Now I carry a M-9, with a CX-4 Storm under the back seat. Interchangeable magazines rock!

[highdiver_2000]

I was trying to think of that website where the old guuy did that test with drywall and a whole bunch of different calibers.

Also, doesn't Ammo-Oracle give a heads up on what works where and why?

http://www.theboxotruth.com/docs/theboxotruth.htm

[highdiver_2000]

Singapore Armed Forces Commandos. Nearest to camera is a P90 with silencer, man on right is holding an Ultimax 100. Two others in the rear with SAR-21

[RamQan]

Having carried a pistol (M-9 or M1911), rifle (M-16, A1 & 2) and shotgun as "assigned weapon" as an Army Medic & Navy Corpsman, I would have jumped at the chance of having a short barreled, large capacity fast firing weapon that could be fired 1 handed. Saddly, it never happened. Back in mid-80's our Tank crews still carried M-3 Grease Guns. Those were fun!

Now I carry a M-9, with a CX-4 Storm under the back seat. Interchangeable magazines rock!

Would you rather have had a Magpul PDR (5.56 nato/6.8 rem/6.5 mm grendel), Mtar-21 (5.56 nato) or Steyr Aug commando (5.56 nato) instead of the CX-4?

[GazB]

My brother went from a 9mm Sterling SMG to a Steyr in 5.56mm.

He liked the Steyr... said it was much more powerful and accurate than the Sterling.

[DocFrench]

Would you rather have had a Magpul PDR (5.56 nato/6.8 rem/6.5 mm grendel), Mtar-21 (5.56 nato) or Steyr Aug commando (5.56 nato) instead of the CX-4?

I'm retired now and while Arizona has some of the best gun laws in the US, they still have issues with full auto. In a perfect world, i'd take the AUG (becauds of barrel interchangeability) or the P-90. Short barrel 5.56 isn't new, look up Bushmaster Arm Pistol from 70's Vietnam conflict.

[ancientgrump]

Straight blowback SMGs ought to be cheaper than locked-breech assault rifles; I suppose they have that going for them. That's actually one of the more impressive things about the P90 to me; cast aluminum receiver, polymer stock, and no close-tolerance locking mechanism to worry about. The weapon was originally intended to arm the ~60% or so of an army that isn't riflemen, right? It had better be cheap and easy to mass manufacture. Or at least that's how it looks to me on paper. Does anyone know how much it actually costs?

[Geezah]

http://www.theboxotruth.com/docs/theboxotruth.htm

Nice one, that was the guyI was thinking of.

Thanks.......

[Walker-69]

I was going to ask: why not use .45 ACP as a silenced round instead of 9mm? But I think I already found some answers. .45 ACP is obviously more expensive and heavier to carry than 9mm, and here's some more info, straight copy-and-paste from Wikipedia:

"Because all standard .45 ACP rounds fired from handguns or short barreled submachine guns are inherently subsonic, it is one of the most powerful pistol calibers available for use in suppressed weapons since subsonic rounds are quieter than supersonic rounds. The latter inevitably produce a highly compressed shock wave, audible as a loud "crack", literally a small sonic boom, while they travel through the air. Suppressors reduce the audible "report" by slowing and channeling the high speed gas generated by the burning/expanding gunpowder before it exits the muzzle resulting in a muffled "cough". Suppressors of course can not act on a supersonic shock wave generated by the bullet breaking the 1,100 ft/s (340 m/s) sound barrier as this happens after it exits the barrel. The downside to the use of .45 ACP in suppressed weapons is that increasing the diameter of the passage through a suppressor decreases its efficiency—thus, while .45 ACP is among the most powerful suppressed pistol rounds, it is also one of the loudest. Most .45 suppressors must be fired "wet" (with an ablative medium, usually water) to bring sound levels down to "hearing-safe" (under 140 dB, generally)."

[Van Gogh]

lighter weapon (with the sacrifice of range) with suppressive fire capabilities for quick storm and standoff missions preferably indoors, close quarters, or light/fast missions.

[NCOres]

lighter weapon (with the sacrifice of range) with suppressive fire capabilities for quick storm and standoff missions preferably indoors, close quarters, or light/fast missions.

That's right and says most of it. SMG bullet is potentially more stable than 5.56 when fired suppressed so it might be preferred. SMGs (MP5s) are slightly easier to control than m4s, and have a lot smaller recoil than 7,62x39 or bigger rounds. That's useful for shot placement in CQC enviroment (multiple targets, fast and accurate fire). It's "painting the target" kind of fire.

It's biggest disadvatages are: bad characteristics against body armor, small range of fire, tendency to ricochet, heavy round in comparison to the range and energy. 9mm 30rd mags take less space on your gear but weight almost the same as 5,56, weight of the weapon is similar too.

[Difool]

lighter weapon (with the sacrifice of range) with suppressive fire capabilities for quick storm and standoff missions preferably indoors, close quarters, or light/fast missions.

I see it more as an enhancement of firepower from a pistol.
It's more suitable for law enforcement units where the firepower of rifles is too dangerous in urban surroundings.
Plus vehicle crew members need small weapons.

[Bacon]

It's more suitable for law enforcement units where the firepower of rifles is too dangerous in urban surroundings.

Read some previous posts in this thread.