Firearm questions?

So if SMGs fire pistol-calibre rounds, what's the difference between an SMG and a 'machine-pistol'? Does the machine-pistol fire lower-powered 'pistol calibre' rounds than an SMG? Is this just a matter of different nations (or maybe manufacturers) choosing different labels for the same concept?
 
Sometimes it's just a case of nomeclature. For example the H&K MP5 is classed as an SMG by most users, but the MP in its name stands for the German for machine-pistol.
 
Eh, I knew it was something that started with "R". :p The 7.62x54R round is still used today for the Dragunov SVD sniper rifles.

Yeah, and with one of them or a Mosin-Nagant rifle you can get a lot of rounds for very cheap. I've seen 'em as low as $50 for 440 rounds sealed in a tin, but it's all shitty corrosive ammo. Combine that with the wooden stock and they take a lot of maintenance to keep 'em nice.
 
Sometimes it's just a case of nomeclature. For example the H&K MP5 is classed as an SMG by most users, but the MP in its name stands for the German for machine-pistol.

Yeah, the problem with guns/ammo nomenclature is that there aren't any real standards that permeate every nation/category. Look at the 9mm/.38/.380/.357.

It can actually be kind of amusing; a guy in the Army tried to tell us that he loaded 7.62 rounds from an insurgent's confiscated weapon into a 240B round by round, since he was out of belted ammo. A couple people were impressed until I said it was impossible, and stupid. He didn't realize that while both use a "7.62" round, the AKM/AK47 weapons use a shorter, tapered round than a 7.62x51 NATO, which is a .308 case.

Another tricky ammo problem is the 5.56/.223. Same exact dimensions on the two rounds, but a 5.56 is loaded for higher pressures, and firing it through a barrel that is only rated for .223 can be extremely dangerous.
 
Yeah, the problem with guns/ammo nomenclature is that there aren't any real standards that permeate every nation/category. Look at the 9mm/.38/.380/.357.
And then there was the situation with mortars: After NATO had standardised on 81mm the PRC decided that their new mortars (to be supplied to insurgents and client regimes in various countries, as well as used by their own forces) would be 82mm instead, thus allowing them to use captured 'NATO' ammunition -- albeit at slight penalties to range and accuracy because of that increased windage -- but not vice versa...
 
And then there was the situation with mortars: After NATO had standardised on 81mm the PRC decided that their new mortars (to be supplied to insurgents and client regimes in various countries, as well as used by their own forces) would be 82mm instead, thus allowing them to use captured 'NATO' ammunition -- albeit at slight penalties to range and accuracy because of that increased windage -- but not vice versa...

Yep. And there's the guys who think you can put a 40mm round from a belt meant for a Mk-19 into a 203 and be just fine... :eek::rolleyes:
 
So if SMGs fire pistol-calibre rounds, what's the difference between an SMG and a 'machine-pistol'? Does the machine-pistol fire lower-powered 'pistol calibre' rounds than an SMG? Is this just a matter of different nations (or maybe manufacturers) choosing different labels for the same concept?

As others have stated, it's often just a matter of nomenclature. However one possible point of distinction is that submachineguns often have a stock and a somewhat longer barrel than a machine-pistol, making their effective range a little greater. The Czech Skorpion, for example, while it does have a folding stock, is so short and stubby that I think it deserves the title "machine-pistol" much more than "submachinegun". Same goes for things like the mini-Uzi and micro-Uzi (or the infamous Mac-10), I'd be reluctant to call them SMGs because they have an accurate range best measured in inches rather than feet. The MP-5 SMG and its variants, despite firing a small round, are quite accurate weapons and part of the reason for that is a longer barrel. The shoulder stock helps with controlling them as well, although full-automatic fire rather than short bursts would still be a bit of a problem I imagine. With a machine-pistol, the emphasis often seems to be on small size and autofire rather than any other concerns.
 
And then there was the situation with mortars: After NATO had standardised on 81mm the PRC decided that their new mortars (to be supplied to insurgents and client regimes in various countries, as well as used by their own forces) would be 82mm instead, thus allowing them to use captured 'NATO' ammunition -- albeit at slight penalties to range and accuracy because of that increased windage -- but not vice versa...

The whole calibres discussion verges on the farcical sometimes. Viktor Suvoros, in "Inside the Soviet Army", has a pretty good discussion on the subject which boils down to something like this: in the USSR, weapons that had different jobs used different calibres just to make logistics organisation easier. For example having pistols, rifles and machineguns all using rounds 7.62mm in diameter but with differing lengths was too confusing, so they got different designations. Whereas in the west, wildly different weapons all used the same caliber. At one point NATO had 120mm mortars, recoilless rifles, and tank guns in service simultaneously. But be careful, because there were rifled and smoothbore tank guns, and the ammunition in one couldn't be used in the other. Getting on the phone to Div HQ and screaming "we need 120s!" to drafted drama students, while spetsnaz were roaming around behind the lines, rockets were landing on road junctions and air raids keep happening is just a recipe for confusion is the point he makes.
 
Never underestimate it...

Eh, I knew it was something that started with "R". :p The 7.62x54R round is still used today for the Dragunov SVD sniper rifles.

Never underestimate that cartridge. That was the only cartridge that was still adopted by any nation that had no significant change into it since 1890s(that means oldest production cartridge still adopted by major military power in the world)...:)
 
Sometimes it's just a case of nomeclature. For example the H&K MP5 is classed as an SMG by most users, but the MP in its name stands for the German for machine-pistol.

Yeah, like AR (assault rifle) for American, STG (sturmgewehr) for some German speaking country and A (avtomat) for Russian...:)
 
What defines how much power a single cartridge has? Its accuracy? The recoil it produces?
kinetic energy of course: (speed in m/s)² . (weight of the bullet in g) / 2000 = energy in Joules (J)
in short: Ek = 1/2 m . v²
not sure how to get ft-lbf out of there with those inconvenient unit relations

f.e.:

9x19mm = ~500J (average for pistols, would be very low powered for rifles)
5.56x45mm = ~1600-1700J (medium power)
7.62x39mm = ~1900J (medium power)
7x43mm = 2440J (intermediate power)
7.62x51 & 7.62x54R = ~3300-3700J (full power)

and two extremes:

6mm Flobert = ~45J (ridiculously low power by any standard)
14.5x114mm = 22000-24000J (totally Badass power level)
 
What defines how much power a single cartridge has? Its accuracy? The recoil it produces?

The accuracy is determined by things like how much tolerance there is in the bullet manufacture, the weapon itself, where the round is headspaced from, etm.

Xavier has covered how the power is determined.
Recoil is largely a product of the power, and is relative to the weight of the weapon as well as the action.
 
The accuracy is determined by things like how much tolerance there is in the bullet manufacture, the weapon itself, where the round is headspaced from, etm.

Xavier has covered how the power is determined.
Recoil is largely a product of the power, and is relative to the weight of the weapon as well as the action.

Uhhh... can I ask you to simplify this into terms that I (with the little knowledge of firearms gleaned from CoD and BF3) can understand? :eek:
 
Uhhh... can I ask you to simplify this into terms that I (with the little knowledge of firearms gleaned from CoD and BF3) can understand? :eek:

Let me try...

The tolerance is how much variation there is in bullets. Meaning if you cast your own bullets and some of them are differently sized by more than a few thousandths of an inch, they can lose accuracy.

Headspace is where on the round the chamber of the gun is pushed up against. Straight cases usually headspace off the mouth of the cartridge (brass) where the bullet is seated; many shouldered bullets headspace off the shoulder (unless it's a belt fed weapon, which often headspace on the belt.)

Recoil is the force caused by Newton's 3rd law. As the bullet is propelled forward, the motion pushes backward. The amount of inertia depends on how fast the bullet leaves the barrel, how much the bullet weighs (grains), how much the weapon weighs (heavier weapons 'absorb' some of the force of the recoil), and how the bolt works (the 'action'). If the weapon is a bolt action, or a revolver, for instance, all of the recoil is transferred from the weapon to the hand or shoulder holding it (other than what is 'absorbed' by the weapon). In a open-bolt machine gun, however, the bolt which is pushed back by recoil can absorb some of the recoil by the motion of it sliding back in the weapon.

In an AR weapon, there is a 'buffer assembly' which consists of a large spring and a 'buffer', which holds a typically tungsten weight inside it. This assembly is designed to absorb even more of the recoil, which is why an M16 has less recoil than a mouse fart.

Any other questions? I'm not good at breaking things down into formulas like Xavier apparently is. I could probably find formulas and more accurate terms if I looked online, Wikipedia and so forth, but I'm just going off memory here.
 
Pedersen developed a mechanism to turn the American 1903 Springfield into a .276 caliber 20 round magazine selective fire rifle between 1917-early 1930's (continual development but it was about to go into full production when World War I ended, that would clearly be an assault rifle. A Mexican Army officer created a pretty good semi-automatic battle rifle that went into limited production by 1910 (the Mexican Revolution's resource demands doomed it, not technical issues.) The Thompson submachine gun was mostly developed in 1918 as a "trench broom" and it's first production model was out in 1919 but the 1921 model is considered when they'd got it right. .

The Mexican gun was the Mondragon.

There is a little confusion here about what Pedersen developed. The Great War conversion of the M1903 Springfield was the "Pedersen Device". It replaced just the bolt of the Springfield and needed a small port cut into the receiver for cartridge ejection. The "Device" looked a lot like the top half of an automatic pistol with a long stick magazine out the top / side. It fired a small .30 caliber pistol round that was not used elsewhere and was considered so secret that all the spent brass was collected in testing.

The Pedersen Rifle was a recoil operated gun (rather unusual) that fired a .276 Pedersen cartridge. It was a competitor to the M1 Garand and luckily for USA, the Garand was chosen. Recoil operated guns don't tend to hold up well.

- Ivan.
 
Quick primer

*Modern cartridges have four parts: a bullet, or the piece of metal being thrown out of the barrel of the gun; the primer which is what the hammer activated by the pull of a trigger hits to initiate the spark to set off the round; the gunpowder activated by the ignition of the primer which is now largely smokeless instead of looking like Revolutionary or American Civil War reenactments; and the casing which holds the whole thing together.
*Modern cartridges are a results of the evolution of 50+ years of technological development during the early/mid 19th century and without major changes in the TL I think the first truly recognizable modern cartridges are introduced in the Lebel rifle of France circa 1882, please correct me if I am mistaken. The components are around individually earlier than this but not as a combined package.
*Assault rifles have selector switches, in the West it usually means three-shot burst, for at least one Russian rifle (AN-94) it may be a two-round burst. They also tend to have intermediate power rounds but not always.
*Automatic rifles can fire repeatedly with holding down the trigger but they often lack selector switches.
*Mondragon's rifle was ahead of its time but suffered from available technology. Germany evaluated it as did Switzerland prior to WWI.
*The MP18 is considered one of the first submachine guns, which use pistol ammunition en masse.
*7.62x54R = Dragunov, but it is also *very* close to the .30-30 round made famous by the Winchester 1894 (7.62x51R) and very close to the 7.62x51 rounds used by NATO. The ballistics are supposedly very similar to the old .30-06 round (.30 caliber bullet introduced in 1906 for those who are less familiar with firearms).
*Because of "spitzer bullets" with pointed ends being a problem for lever-action rifles you will not see most modern military ammunition in lever-action rifles, the pointy ends of the bullets potentially can set off every bullet in front of them
*Bigger numbers are not always better. A .22 long (rifle) round is not the most powerful out there, and a .223 may not sound much better but it is the M16 round and is more powerful than a .32 (pistol) round, a .40 (pistol) round, and a .45 (pistol) round. Meanwhile a .308 is still more powerful than any of the aforementioned, and depending on the round a .50 caliber can be more powerful still. Then again there is a .50 pistol round and a .50 rifle round as well.
*Many high-cap pistols have staggered-column magazines which lets you have roughly double the ammo without having to double the clip size. I think this was first introduced as Browning's Hi-Power pistol circa 1935 with designs of his dating back into the late 10s or 20s.
*Bullpup rifle: clip is behind the trigger (look up Styer AUG for an example)
 
Sometimes it's just a case of nomeclature. For example the H&K MP5 is classed as an SMG by most users, but the MP in its name stands for the German for machine-pistol.
Sometimes, yes, but many machine pistols do have the magazine in the grip, while most sub-machine guns stick the magazine out in front of the grip somewhere.
 
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