What is the purpose of sub-machine-guns?

[RamQan]

Hello

First I would like to say I don't know much about firearms, I've fired a few types (pistols, carbines, machine-guns etc.), but that is all. This thread is not about me trying to convince anyone else something, it's about have a constructive discussion.

I wonder what role a sub-machine-gun fills and why you don't just use a carbine instead.

The shortest Steyr Aug is 63 cm overall length, with 35 cm barrel. This is shorter than standard mp5's and only 13 cm longer than a P90.

I am aware of the use by special forces as easily concealed and easily silenced fire-power. I am also aware of police use to avoid over penetration and harming innocent.

What I don't understand is why many armies buy Mp7's and similar weapons. What benefit does a regular soldier get from carrying an SMG?

[Bro Jangles]

before the advent of the intermediate cartridge they were used for a infantry weapon with a high rate of fire for close fighting. now adays most are used as specialty weapons, meant for CQB, or a secondary for heavy weapons users.

[RamQan]

before the advent of the intermediate cartridge they were used for a infantry weapon with a high rate of fire for close fighting. now adays most are used as specialty weapons, meant for CQB, or a secondary for heavy weapons users.

Yes, I know that. The Germans invented the StG44 in 1944 and made the smg obsolete in that role. You mentioned CQB, this is exactly what I wonder, aren't you better of with a 63 cm long Steyr Aug than any SMG? What benefits would something like a P90 have over a 63 cm Steyr Aug in CQB?

[Van Gogh]

close range, light, high speed warfare.

[commanding]

Hello

First I would like to say I don't know much about firearms, I've fired a few types (pistols, carbines, machine-guns etc.), but that is all. This thread is not about me trying to convince anyone else something, it's about have a constructive discussion.

I wonder what role a sub-machine-gun fills and why you don't just use a carbine instead.

The shortest Steyr Aug is 63 cm overall length, with 35 cm barrel. This is shorter than standard mp5's and only 13 cm longer than a P90.

I am aware of the use by special forces as easily concealed and easily silenced fire-power. I am also aware of police use to avoid over penetration and harming innocent.

What I don't understand is why many armies buy Mp7's and similar weapons. What benefit does a regular soldier get from carrying an SMG?
I think you have to realize that sub machine guns were developed prior to the advent of the smaller carbines. Additionally, submachine guns as you know, use pistol ammo, which is generally smaller (takes up less space) and lighter weight (for carrying), as well as the lightness of the weapon itself.
In WWII, sub machine guns were used for just that reason, more ammo, less weight, but good in close in fighting and for suppressive fire. They have been carried on until today in various capacities, both military and civilian.

[little icebear]

Nowadays? In the military? Only for speciality roles. Doorkicker stuff, boarding parties etc...

Submachineguns make sense for policework, they are not important for infantry stuff as far as I can tell.

[ayanami_tard]

during WWI there is a requirement for a firearm(i said firearm.polearm and entrenching tools can be used and have been used either but that ain't firing any round) that can be used to clear out trench.

[RamQan]

close range, light, high speed warfare.

Isn't that what carbines are for?

Weight:
3,2 kg (empty Steyr Aug) ,
3.1 kg (M4 carbine loaded with 30 rounds,
3,0 kg (P90 loaded with 50 rounds.
1,9 kg (empty MP7)

The difference isn't that great.

[ayanami_tard]

btw mp-7 was designed with assailant wearing body armor in mind

[little icebear]

What I don't understand is why many armies buy Mp7's and similar weapons. What benefit does a regular soldier get from carrying an SMG?

Most of the time? None. Makes little to zero sense and I´m not really happy when I see our soldiers slinging those things on dismounted patrol in Afghanistan.

They are light. That´s the only "advantage".

I´m even tempted to say that the carbine-length is overhyped. Unless you know that you´ll be doing house to house fighting most of the time, you´re better off with a full size rifle.

Flame away.

[RamQan]

btw mp-7 was designed with assailant wearing body armor in mind

A 5,56 mm is still better at penetrating body armour.

"The Bundeswehr (http://en.wikipedia.org/wiki/Bundeswehr) began to procure the MP7 in high numbers[2] (http://en.wikipedia.org/wiki/MP7#cite_note-1) after seeing its use by the special forces unit Kommando Spezialkräfte (http://en.wikipedia.org/wiki/Kommando_Spezialkr%C3%A4fte) (KSK), where it has been used extensively. German soldiers in Afghanistan (http://en.wikipedia.org/wiki/Afghanistan) are now using the MP7 on patrol in Kabul (http://en.wikipedia.org/wiki/Kabul). The MP7 is also a part of Germany's Infantryman of the future (http://en.wikipedia.org/wiki/IdZ) project."

^^ That is what I find so weird, why go around patrolling Kabul with a 4,6mm "pistol"?



They are light. That´s the only "advantage".

Ok

[little icebear]

^^ That is what I find so weird, why go around patrolling Kabul with a 4,6mm "pistol"?



Stupidity. Nothing else.

[Bro Jangles]

Yes, I know that. The Germans invented the StG44 in 1944 and made the smg obsolete in that role. You mentioned CQB, this is exactly what I wonder, aren't you better of with a 63 cm long Steyr Aug than any SMG? What benefits would something like a P90 have over a 63 cm Steyr Aug in CQB?
well alot of forces are tradeing in thier MP5s for 10 inch barrel carbines. US special forces are using the MK18CQB, and i believe the brits are doing the same with the C8CQB(dont know the british designation) and alot of US Swat teams are doing the same. now you asked about the P90, benefiets of that are since it is bullpup, it has a good barrel length for a PDW and it has a 50 round mag, which is huge. but you are confusing a SMG for a "PDW" smg = pistol caliber automatic weapon, PDW= the modern pdw is usually a smaller rifle caliber, 5.7, 4.6, and is intended to penetrate body armor at close ranges were the 9mm may have problems.

[SMGLee]

P90 and MP7 were initially developed as a rear echelon support weapon, that is why it is called the Personal Defense Weapon. it was developed with min effort to shoot, easy to aim and place hits out to 200m and ability to penetrate spetsnaz armor. since original role of spetsnaz were to criple the NATO supply line in the advent of a Western European war.

So the P90 and MP7 are more for the support troops instead of Special Operation group, but the compact and high rate of fire also made it suitable for SOG troops until actual shoot resulted in inability to neutralized a threat. US Secret Service no longer deploy the P90 in numbers like they did five years ago...that would be a sign!

[budgie]

Yes, I know that. The Germans invented the StG44 in 1944 and made the smg obsolete in that role. You mentioned CQB, this is exactly what I wonder, aren't you better of with a 63 cm long Steyr Aug than any SMG? What benefits would something like a P90 have over a 63 cm Steyr Aug in CQB?

I'm no expert, but I can read. It seems there has been a progression of sorts based on 'competition' between the good guys and the bad.

Part of the appeal of SMGs among SWAT teams, HRT and other door kickers seemed to be the low power of the cartridge: a pistol bullet would stop when it hit a tango, or a wall, and wouldn't be such a danger to civilians/hostages. With better body armor becoming available on the open market, rifle calibers (like .223) became more popular; with improved ballistics, subsonic rifle rounds proved a better compromise between safety and penetration.

Nowadays an anti-terror squad can expect the baddies to have body armor, so a carbine offers better penetration; sensible choice of ammo mitigates danger to bystanders.

[Bacon]

US Secret Service no longer deploy the P90 in numbers like they did five years ago...that would be a sign!

Thanks for the info, I didnt know they cut back on the P90.



Part of the appeal of SMGs among SWAT teams, HRT and other door kickers seemed to be the low power of the cartridge: a pistol bullet would stop when it hit a tango, or a wall, and wouldn't be such a danger to civilians/hostages. With better body armor becoming available on the open market, rifle calibers (like .223) became more popular; with improved ballistics, subsonic rifle rounds proved a better compromise between safety and penetration.

Nowadays an anti-terror squad can expect the baddies to have body armor, so a carbine offers better penetration; sensible choice of ammo mitigates danger to bystanders.

FBI tests revealed that the 5.56 round did not over penetrate as much as SMG rounds.

I'm no expert either, I just play one on TV.

[Walker-69]

There might be one niche use for submachineguns. That is, when a silencer/suppressor is used. I would imagine, with my little knowledge of firearms, that a bigger calibre such as .45 ACP would be more practical with a silencer, because the bullet is heavier. I have the impression that in the Finnish army, though, they use ordinary 9mm rounds with SMGs with silencers. "Just like in the Bond movies" ya know. p-)p-)p-)p-)p-)

5.56 with a silencer would be a very bad combo because the whole idea of the original design behind 5.56 NATO is to have a high-speed bullet. A silenced bullet needs to travel under the speed of sound.

[Walker-69]

Here is one approach to a suppressed SMG, straight from Wikipedia. Remember, a supersonic round creates a 'crack' in flight because of the sonic shock wave: a subsonic round creates no crack. But a subsonic round is not silenced unless the explosion is also muffled at the end of the barrel. Anyways, a cut-and-paste from Wikipedia:

- - - - - - - - - - - - - - - - - - - - - - - - - - -

In 1974 H&K initiated design work on a sound-suppressed variant of the MP5, designated the MP5SD (SD – Schalldämpfer German for "sound dampened"), which features an integral but detachable aluminum sound suppressor and a lightweight bolt. The weapon's 146 mm (5.7 in) barrel has 30 2.5 mm (0.1 in) ports drilled forward of the chamber through which escaping gases are diverted to the surrounding sealed tubular casing that is screwed on to threading on the barrel’s external surface just prior to the ported segment. The suppressor itself is divided into two stages; the initial segment surrounding the ported barrel serves as an expansion chamber for the propellant gases, reducing gas pressure to slow down the acceleration of the projectile. The second, decompression stage occupies the remaining length of the suppressor tube and contains a stamped metal helix separator with several compartments which increase the gas volume and decrease its temperature, deflecting the gases as they exit the muzzle, so muffling the exit report. The bullet leaves the muzzle at subsonic velocity, so it does not generate a sonic shock wave in flight. As a result of reducing the barrel’s length and venting propellant gases into the suppressor, the bullet’s muzzle velocity was lowered anywhere from 16% to 26% (depending on the ammunition used) while maintaining the weapon’s automation and reliability. The weapon was designed to be used with standard supersonic ammunition with the suppressor on at all times.

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-Now we are talking about a 9mm MP5 SMG. This is obviously a compromise of a solution for a silenced submachine gun, specialized subsonic ammo with a heavier bullet would be more effective.

[SMGLee]

Only two types of subguns are still popular with the US Special Operation groups, MP5k and MP5SD. the SD are great for sentry removal, the kind of sentry that barks. and also the K is great for driver that want to get someone off his face in a quick manner.

[ARGAR FORKBEARD]

talking of PDWs check this out (if you were un aware)

http://www.magpul.com/pdfs/PDRtech_PR.pdf

must be a bitch with the unburnt powder in such a short barrel!

[SMGLee]

talking of PDWs check this out (if you were un aware)

http://www.magpul.com/pdfs/PDRtech_PR.pdf

must be a bitch with the unburnt powder in such a short barrel!

I would be impressed if that thing ever comes to light!

[HGRazorR]

Can we agree to narrow this question to what is the role of the SMG in present day?

In the military, I've only seen a MP5A3 (or 4 or 5) used by one individual on a Maj Gen's PSD team in Iraq.

NYPD is often seen with them outside Penn Station/ Grand Central when the Threat Level goes up. Smoke 'em if you got 'em I guess, cheaper just to use an MP5 that you already have then refit your inventory with an M4.

[Eknytz]

Wouldn't submachineguns also have less recoil due to their smaller cartridge?

[gaijinsamurai]

Wouldn't submachineguns also have less recoil due to their smaller cartridge?

I don't think that's a big issue. The 5.56 round's recoil is low to begin with, and the M16/M4's buffer makes it minimal.

When I was in the Marine Corps (a long time ago), the only submachineguns I ever saw were MP5SD models, and the only units that had them were Recon and Force Recon, with the units' role to try to avoid contact with the enemy when possible, making silenced weapons advantageous.

[Chulo]

talking of PDWs check this out (if you were un aware)

http://www.magpul.com/pdfs/PDRtech_PR.pdf

must be a bitch with the unburnt powder in such a short barrel!
looks like a P90 mated with a bullpup

[Geezah]

FBI tests revealed that the 5.56 round did not over penetrate as much as SMG rounds.

I'm no expert either, I just play one on TV.

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?

[Chulo]

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?
Dubbed in japanese for your viewing pleasure

http://www.youtube.com/watch?v=F8CuOybgmxQ

9mm, .45acp, .357mag, .44mag, .454 .460 S&W, .50AE etc. Penetration test through wood

[Eknytz]

looks like a P90 mated with a bullpup
The P90 is bullpup.

[Chulo]

The P90 is bullpup.
I was differentiating between the topload feed mechanisms and the "normal" bullpup traditional feed.

[GazB]

When first introduced their purpose was short range firepower.

Low power pistol rounds were used but that was compensated for by being fully automatic.

Hitting fast moving targets was easier with a spray of bullets and hitting the target multiple times made them very lethal.

The ammo is relatively compact though a 9mm round weighs about the same as a modern small calibre assault rifle round, the muzzle blast from a 9mm round from a longer barrel than most pistols made them generally more accurate than pistols and easier to learn to use effectively.

This might step on a few toes, but a pistol is a very difficult weapon to master and is therefore not a particularly effective weapon to give to someone who has a job to do that means they can't carry a standard rifle.
To use effectively the range needs to be very close and the shooter needs lots and lots of practise, which most rear area personel in most armies don't get much of either when they need to defend themselves.

It made rather more sense to give such personel a larger and heavier weapon that fired the same ammo (firing the full power ammo of the time would require the ability to shoot accurately and while you spend time training riflemen to shoot accurately, you want to spend time training surgeons to do their job or cooks to do their job properly. The best way around hitting targets will little training is low recoil full auto guns at close range.)

Sometimes the SMG was used as a frontline weapon, like initially storming trenches. Later it found popular use in forests (the Finns) or in Urban combat where the ranges were shorter anyway and if the other guy had a bolt action rifle and you had a SMG then you had a firepower advantage.
For personnel whose role was something other than rifleman however the purpose of the SMG was a small compact weapon using ammo already supplied to armies anyway that had low recoil that could be fired in bursts to make up for the fact that you probably didn't spend all day at the range practising with it, and for the fact that a single hit from a pistol round might not stop the enemy. Most users might go through a whole war without firing a shot in anger, where a pistol would have been lighter if they actually had had to use it it probably would have been so ineffectual they might as well have used the first shot on themselves, and a rifle is too big and heavy and make it harder for them to do their primary jobs whatever that was.
There is much talk about assault rifles combining the virtues of the battle rifle (range, power and accuracy) with the virtues of the SMG (short range firepower, controlability in full auto, increased capacity magazines, lightweight ammo).
They generally do but even the small assault rifles are not really that small for something you might have to carry and never use.

[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

http://farm4.static.flickr.com/3255/3202268785_e5f833a633.jpg

[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 (http://www.militaryphotos.net/wiki/Submachine_gun) are inherently subsonic, it is one of the most powerful pistol calibers available for use in suppressed weapons (http://www.militaryphotos.net/wiki/Suppressor) since subsonic rounds are quieter than supersonic rounds. The latter inevitably produce a highly compressed shock wave (http://www.militaryphotos.net/wiki/Shock_wave), audible as a loud "crack", literally a small sonic boom (http://www.militaryphotos.net/wiki/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 (http://www.militaryphotos.net/wiki/Ablation) 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.