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Both can fire in semi auto and full auto. So, for us normal people, once and for all, what's the difference(s) between a sub-machine gun and an assault rifle?

I think it's a matter of caliber. I mean, don't SMGs use pistol rounds?

I believe it's a matter of range and, depending, caliber.

I also think it's a matter of CQB, with SMGs allowing easier and more flexible use in close quarters than an assault rifle, which of course has longer range.

It's their bullets. Carbines can be as big as submachine guns, the FAMAS is quite small but it is also a rifle, not an SMG. An SMG uses pistol rounds. Well, except the P90, which has its own special round, but it still ain't a rifle bullet.

SMGs are primarily light automatic weapons specifically made for close quarters fighting. Most of them fire standard pistol ammo such as the 9mm although their are a few exceptions to that. Effective range is mostly around 50 to 100 meters although some can make 200 meters.

Assault rifles are larger and longer barreled automatic weapons that fire much more powerfull ammo and they are designed for ranged combat out to around 600 meters.

Stormbringer wrote:I believe it's a matter of range and, depending, caliber.

Submachineguns are also smaller than assualt rifles and weigh less.

A carbine fires full caliber assault rifle ammunition (generally 5.56x45 or 5.45x39), and as a rule is simply a rifle with a short barrel and usually a collapsible buttstock. For all intents and purposes it is simply a "handier" rifle, in that one can more easily maneuver it quickly and in tight spaces. For many uses and in medium-range combat there is no functional difference between a carbine or a rifle, either one would do. Naturally, a carbine is a bit lighter than a full-length rifle. The one way that they do differ significantly is that a carbine, by nature of its shorter barrel, fires the same round at slightly slower speeds. This is usually not a big issue, but can be severely detrimental in such weapons as the M4, where the 5.56x45 cannot be trusted to reliably fragment under all conditions.

Note that one does not base carbines off of full-size cartridges like the 7.62x51 NATO or 7.62x54R Warsaw Pact rounds fired by battle rifles such as the HK G3, M14, FN FAL, and so on. Carbines are, to my knowledge, based exclusively on assault rifles.

A submachine gun, on the other hand, fires ammunition identical to a pistol. While a carbine is much like a rifle, a SMG is in many respects an automatic pistol with a longer barrel and a buttstock. Due to the inherit differences between a rifle and a pistol round, a SMG is very poorly suited to anything more than short-medium range combat (really, anything over perhaps 150m). On the plus side, the SMG's smaller round allows it to be much more controllable on full automatic than is a carbine or rifle, which usually rely on 2- or 3-round bursts to get the job done. Since the range of a SMG is by nature rather poor, retractable buttstocks do not get the attention of a carbine's: they are often lighter, flimsier, and in almost every respect inferior (the point, of course, to save weight and size). The SMG is the handiest of the three weapons at very close range, being lighter and shorter than a carbine. It can also be as effective (if not more effective) at such ranges, when the velocity of the round has not fallen off significantly.

For comparison:

Full length assault rifle, Heckler und Koch HK33

Carbine (shortened rifle with collapsible buttstock), Heckler und Koch HK53

Submachine gun, ubiquitous HK MP-5N

The pistol grip is identical on all three weapons, to give one an idea of the scale we're talking about.



Note: The HK53 has a very small and short buttstock by carbine standards. It was chosen for this because the HK standard pistol grip gives a good idea of scale. A more typical retractable buttstock is that on the AKS-74U or Colt M4 (image 2).

Most firearms combat takes place at distances under 300 m and the great majority of that portion at ranges under 200 meters. A sniper with a rifle built for the purpose is about the only type of soldier who will regularly engage enemies at ranges exceeding 400 m, and is the only type of soldier with a prayer of hitting the target at that range. Don't have much else to add to the definitions of AR and SMG. SMGs are really handy in urban fighting when you have to enter buildings, rifles tend to get in the way, but if the enemy is wearing body armor, its effectiveness drops significantly.

Edi

Since no one else has mentioned this yet, rifles have helical grooves on the inside of the barrel which make the bullet spin, thus giving it better accuracy, hence the term "rifled barrel".

The most crucial difference, I think, between the three is barrel length. Calibre, not so much, because you have assault rifle bullets being used in sub-machine guns (the AKS-74U being a prime example).

Shroom Man 777 wrote:It's their bullets. Carbines can be as big as submachine guns, the FAMAS is quite small but it is also a rifle, not an SMG. An SMG uses pistol rounds. Well, except the P90, which has its own special round, but it still ain't a rifle bullet.

Actually, the 5.7x28mm SS190 round used by the P90 is still technically a pistol round despite it's shape: It is also used by the Five-seveN handgun. The SS190 is also smaller than the .357 Magnum, which is indisputably a pistol round (the .357 has a 36mm-long case).

Darth Wong wrote:Since no one else has mentioned this yet, rifles have helical grooves on the inside of the barrel which make the bullet spin, thus giving it better accuracy, hence the term "rifled barrel".

SMGs and handguns also have rifling. I don't think there are any smoothbore handguns or SMGs on the market.

Vympel wrote:The most crucial difference, I think, between the three is barrel length. Calibre, not so much, because you have assault rifle bullets being used in sub-machine guns (the AKS-74U being a prime example).

Regardless of what it's referred to, the AKS-74U is still technically a rifle (or carbine, if you will) on account of the round it fires, as is the Colt Commando (which is marketed as an SMG). The 5.56mm G36C, on the other hand, is marketed as a "compact assault rifle" by H&K, despite the fact that it is just as small as either. A nice example of the line between SMGs and ARs/carbines is the Steyr AUG: in normal form, it fires 5.56mm NATO, and is a referred to as an assault rifle. However, it can easily be converted (with the proper parts, of course) to fire 9mm Parabellum, and when in this form it is known as an SMG.

All guns bar shotguns (unless choked to fire slugs) are rifled. They can be standard rifling grooves or the more modern polygonal rifling used today. This aids their range and accuracy by spinning the round so as to gyroscopically stabilise it in flight without the need for fins.

Admiral Valdemar wrote:All guns bar shotguns (unless choked to fire slugs) are rifled.

What modifications are necessary to allow shotguns to fire slugs (aside from adding rifling to the barrel)? I assume that "shot" can't be fired from rifled barrels, because it would wear down the rifling, correct?

Ma Deuce wrote:

Admiral Valdemar wrote:All guns bar shotguns (unless choked to fire slugs) are rifled.

What modifications are necessary to allow shotguns to fire slugs (aside from adding rifling to the barrel)? I assume that "shot" can't be fired from rifled barrels, because it would wear down the rifling, correct?

You can fire shot from rifled shotgun barrels still, but it's not going to help given it won't affect the projectiles, but some older shotguns had rifled barrels as standard from what I recall. Most modern ones have individual components that are inserted in the barrel to act as rifling and work with the slugs used commonly by law enforcement agencies to take doors down by blasting the hinges clean off, the SPAS-12 for instance.

Modifications? Can't all shotguns use slugs? They have buckshots, which are really nasty, and slugs which can take heads off, right?

If you want the slug to fly anywhere with any degree of accuracy, it's best to have a choked barrel mod for rifling. But since most uses for this round are close range high-power punches, range and accuracy isn't a problem often.

Stormbringer wrote:I believe it's a matter of range and, depending, caliber.

What he said.

Isnt AKSU considered an assault carbine rather than a submachine gun?

I always thought that SMG's use pistol amunition, while rifles use rifle or semi-rifle ammo (like Ak47)

Vympel wrote:The most crucial difference, I think, between the three is barrel length. Calibre, not so much, because you have assault rifle bullets being used in sub-machine guns (the AKS-74U being a prime example).

That's pretty much a lone freak that isn't considered in such things, only some books classify it as an SMG in the first place. Anyway, the Steyr IWS2000 is smoothbore yet still gets grouped with sniper rifles. The traditional rule is that submachine guns fire pistol cartridges, assault rifles fire immediate sized cartridges and plain old rifles fire full size cartridges. Accurate range can also come into things but its much less important. There's really no reason to completely throw away these 99% accurate definitions just for a handful of freaks.

Annoying stuff like that is how you go from dividing up artillery into mortars, guns and howitzers to grenade throwers, mortars, guns, cannon, rifles, gun-howitzers, howitzers and I know I'm missing one or two more. Such distinctions do have purpose, but it's not the sort of thing you worry about often.

EmKay wrote:Isnt AKSU considered an assault carbine rather than a submachine gun?

Actually, AKS-74U's very designation clasifies it as a rifle, rather than an SMG as it is popularly called. After all, AK=Avtomat Kalashnikova=Kalashnikov Automatic Rifle. The S refers to the folding buttstock, and the U=Ukorochennyj=Shortened

Most true SMG's produced in Russia have the letters PP(Pistolet Pulemjot=Submachinegun) in their designation. Examples are the WWII-era PPSch-41, or the recent PP-93.

Well, no one has mentioned this, which is one of my biggest annoyances, so I'll just tackle it here. There is no class of weapons called an assault rifle. Stop saying that. NOW.

There are combat rifles, and battle rifles (which fire larger-calibre rounds), but assault rifle is just a generic, lazy-man term for sticking them together. Much as you will never see or hear me say "clip," I don't say "assault rifle" or "silencer."I always use correct terminology. And if you don't, I'll bitch about it for a while, and leave to go sulk somewhere.

Howedar wrote:as a rule is simply a rifle with a short barrel and usually a collapsible buttstock.

I'd simply go with a rifle with a shorter barrel; none of your bullpup carbines have collapsible buttstocks; and some of the others like the Soviet AKS-74U simply have a side-folding skeleton stocking.

Howedar wrote:For many uses and in medium-range combat there is no functional difference between a carbine or a rifle, either one would do.

Definitely a difference given the twist and balance of the current Belgian 5.56x45 round.

Howedar wrote:This is usually not a big issue, but can be severely detrimental in such weapons as the M4, where the 5.56x45 cannot be trusted to reliably fragment under all conditions.

You mean penetrate or tumble?

Howedar wrote:Note that one does not base carbines off of full-size cartridges like the 7.62x51 NATO or 7.62x54R Warsaw Pact rounds fired by battle rifles such as the HK G3, M14, FN FAL, and so on. Carbines are, to my knowledge, based exclusively on assault rifles.

The initial round of NATO rifles with the 7.62x51 round are still considered assault rifles, I believe. Although I have heard the M14 refered to as a "battle rifle."

Oh, and H&K did make a carbine G3.

Howedar wrote:It can also be as effective (if not more effective) at such ranges, when the velocity of the round has not fallen off significantly.

I think you'd be hard pressed to find a 9 mm or .45 SMG that will reliably penetrate body armor without multiple hits even at relatively close range.

YT300000 wrote:Well, no one has mentioned this, which is one of my biggest annoyances, so I'll just tackle it here. There is no class of weapons called an assault rifle. Stop saying that. NOW.

How about no?

There are combat rifles, and battle rifles (which fire larger-calibre rounds), but assault rifle is just a generic, lazy-man term for sticking them together. Much as you will never see or hear me say "clip," I don't say "assault rifle" or "silencer."I always use correct terminology. And if you don't, I'll bitch about it for a while, and leave to go sulk somewhere.

You know; before you go on a rant about correct terminology, make sure your correct in the first place. Assault rifle is a class of weapons, which stems from Sturmgewehr, the name coined for the first weapon of the type, the MP-43 to help sell it to Hitler. Combat Rifle is as vague a term as Battle Rifle and has been applied to everything from experimental Flechette launchers to the M1 Garand to bolt action weapons.

If you want to be a terminology whore then you should understand the fact that when you really get down to it none of these classifications are anything more then terms of conveiance and from a technical standpoint only bolt action and automatic rifles exist among modern military arms. So cut the bitching and live with it.

YT300000 wrote:Well, no one has mentioned this, which is one of my biggest annoyances, so I'll just tackle it here. There is no class of weapons called an assault rifle. Stop saying that. NOW.

There are combat rifles, and battle rifles (which fire larger-calibre rounds), but assault rifle is just a generic, lazy-man term for sticking them together. Much as you will never see or hear me say "clip," I don't say "assault rifle" or "silencer."I always use correct terminology. And if you don't, I'll bitch about it for a while, and leave to go sulk somewhere.

This is a bunch of bullshit and you don't know what you're talking about.

While true the original generation of bolt-action and early semiautomatic rifles in the 7-8mm range (the 7.92 Mauser round, the .30-06 Springfield round, the Soviet 7.62x54mm rimmed cartirdge, etc.) were called battle rifles, assault rifles are a type of weapon. Originally refering to the literal "Assault rifle" StG-44, they refer either specifically to selective-fire rifles (capable of full-automatic or burst fire) cambered for intermediate cartridges (full battle rifle cartridges with shortened down cases; ie. the German 7.92x33mm Kurtz, and the AK47's 7.62x39mm) or small-calibre cartridges (the 5.56x45mm NATO round, the 5.45x39mm Soviet). I've also heard it refer more generally to selective-fire rifles in general, including the first generation of NATO rifles in the 7.62x51mm calibre.

Darth Wong wrote:Since no one else has mentioned this yet, rifles have helical grooves on the inside of the barrel which make the bullet spin, thus giving it better accuracy, hence the term "rifled barrel".

That's why rifles are called rifles, but pistols and submachine guns aren't smoothbore either.