SMGs in ww2 with much smaller cartridges?

[peceed]

What is also true is that nobody here has a monopoly on being right on his assumptions. Both of us included.

I have researched the topic ("better pistol ammo for WWII military") and have drawn my own conclusions based on the facts. The limiting factors are:
-limited grip size (human anatomy)
-limited barrel length (ease of use)
-halved ballistic coefficient in supersonic flight (aerodynamics)
-longer ogives reduce muzzle energy - less propellant in the case or barrel capacity for gas expansion (technical tradeoffs)
-not fully understood terminal ballistics (the knowledge of the time)
These factors have kept pistol ammo essentially unchanged for over a hundred years.

Historical submachine guns were quite adequate for combat at ranges of up to 150-200 meters, making up for their lack of accuracy with fire density.

 

[ThomasP]

Why not just using a bullpup arrangement for the SMG? That would solve the barrel length problem (12"-14" should be possible), and limited grip size would not apply.

??

 

[Shortround6]

Don't be sorry, I'm used that people are doubting a lot of my ideas
The ww2 SMGs as-is don't have some big problems, the biggest problem was that people were sometimes too late to introduce them, and in good numbers, in the second half of the 1930s.
What the small-caliber SMG might've offered is the lower recoil, accuracy beyond +-100 m, more ammo to be carried for the same weight. The SMG itself might've been lighter.

A major problem was the desire to use the "standard" pistol cartridge as the submachine gun round to standardize logistics. Whatever most different countries used as a Pistol cartridge.
Or how suitable it may have been (or not been) for the job of a submachine gun/automatic carbine.
The .45 being rather heavy and low velocity (curved trajectory) as two of it's minus marks a 3rd could be recoil (?) but that depends somewhat on the weight of the gun.

To get some idea of where we are at the US Army figures for the .45 automatic show that it retains energy well, penetrating 6in of pine at 25yds and still penetrating 4in at 250yds.
It would also penetrate 10 of loam(dirt) at 25yds and 8in of dry sand.
However the trajectory is a bit of problem. If the shooter is laying on the ground and aims at enemy soldiers feet, he can hit them (the feet) at 300yds but the bullet will be 6 ft high somewhere a bit over 150yds. This also means if he is firing with the gun 3 feet off the ground and aiming at the enemies waist he will (in theory) hit it but at 150yds with the same sight setting, he will be 3 feet over the 6ft solders head. Use at long range (much over 100 yds) requires skill, good sights and quite possibly an observer. All three of which would be lacking in most armies.

Early WW II Thompson sight. and a late war rear sight

Look through the hole at close range and look through the little slot in the top for longer range. For 300yds just hold most of the front sight above the rear sight and pray.
For comparison the US .30 cal carbine round weighed 195 grains vs the .45 auto's 325 grains so there was a considerable savings in weight. In fact the US .30 cal M2 ball fired out of the M-1 rifle weighed about 395 grains.

The German and Soviet pistol ammo would be even lighter but 20-30 (?) lighter than the 30 cal Carbine is not that big a deal.

The 7.62-7.65 X 25 rounds fired at 1300-1500fps (depends on load and barrel length) and the .30 cal carbine was doing 1780fps during the adoption trials. They did get it up to 2000fps for service use using a new powder that also lowered the chamber pressure. Win-Win. Something to consider when thinking about some of these "what if's". The US and some others made a decent jump forward in propellents in the late 30s and 1940.


Trying to use even some of the small "rifle" rounds in the pistols gets difficult, maybe not impossible but difficult. Where I work part time they have 3 pistols chambered for 5.7 x 28.
My hand is just about 20cms long and those pistols do not feel comfortable in my hand. The Grip is too long, I can hold it but I don't like it. Anything any longer gets really strange.

The worlds armies bought a lot of pistols, they issued them by the millions, actual ammo fired by troops out of pistols in combat, is by the lowest ratio of rounds purchased to rounds fired of any class of weapon. In hind sight there was room for a full auto carbine round.

 

[yulzari]

One must consider what is 'better' about smaller diameter faster cartridges. The purpose of the machine carbine is to dominate the gap between pistol arms length/pointy stick range and LMG fire range in a portable cheap small firearm. Say 25 metres to 200 metres. Beyond that you use an LMG and standard infantry rifle. If naughty chappie is over 200 metres away stop firing at him with a machine carbine as you will annoy him and draw his fire. Call upon your crew automatic weapon to make him stop it and go away.

The dangerous area is that within which a bullet fired at the centre of mass has a trajectory which will hit naughty chappie somewhere between ankle and forehead. The full power Tokarev/ Mauser Export 7.62x25mm (or indeed 9x25mm) will do that and, as I have said above, is as powerful as you can accommodate within a simple blowback machine carbine. Job done, home for tea and medals.

Small high velocity rifle cartridges can do wonders in achieving a flatter trajectory but need delayed/locking breeches and generally are more complicated and expensive. They can do that out far beyond the necessary range of a machine carbine. They are a technically correct answer to a question that need not be asked for a machine carbine in this period.

In WW2 they used what they had and it worked. Post war we have ended up with small calibre infantry rifles and shortened versions now cover the machine carbine role all using the standard period rifle ammunition. The British in period used 9x19mm as they were copying the German MP23 initially and the Germans used the same as it was what the Luger P08 used as the standard pistol ammunition and their MP18 used Luger snail drums. Further back the Luger came in 7.63x19mm but a few foreign orders pre Great War wanted a larger calibre so the necked 7.63x19mm was necked out as far as it would go into a straight walled 9x19mm cartridge. The Russians went for the 7.62x25 as they wanted to use shorter cuts of their rifle barrels for machine carbines and had the pistol Tokarev in hand so used that. The Americans went with .45 Auto Colt and the French their 7.62 Long as it happened to be their own pistol ammunition. Actually nobody ever decided to make machine carbines with a special optimum cartridge in the period of the OP. The M1 Carbine was not a machine carbine but a more traditional approach of an infantry rifle lite.

The more energy you get out of the muzzle is more recoil energy that has to be absorbed by the mass of the gun and its bolt mass. Up the energy and you soon run onto the limit of simple blowback. The 7.62/9x25mm turns out to be as good as you get before running into these issues. Once you introduce delayed or locking breeches with all their complicated bit you may as well end up making a short infantry rifle with all it's costs. If the 7.62/9mmx25 cartridge cannot do the job then you are missing the point of the machine carbine. As I have said, this is a mature design inasmuch as it you cannot make a better machine carbine for the role of a simple cheap reliable gun to dominate out to 200 metres. You can today use assorted modern materials to do it in a different way but you are still essentially making the mature design more cheaply and reliably. Just as the latest pistols today are still the same concept as Browning's original locked breech pistol of 1893. Just with better materials.

Today the limiting factor that has removed the machine carbine from the inventory has been the removal of It's role by the modern intermediate standard infantry rifle and the need to penetrate infantry armour. In the OP period these were not in existence in mass use and certainly armour was not an issue. In 1944 the British army was considering keeping their 9x19mm machine carbines and moving infantry rifles and LMGs to 7.92mm Mauser. Soon after the war they sought instead to combine both into one intermediate weapon which is what we see today but that period no9 Rifle was the victim of the old fashioned American desire to shoot horses one mile away. But I digress… What remains is in limited use for close range Police and anti terrorist special forces. On the open mass army battlefield the machine carbine is long out of its window of opportunity. In the OP period however it was in its peak utility but not one in which smaller calibre ammunition would be an enhancement.

The target remains the same and needs a certain amount of energy transferred to poke enough hole into it. To reduce weight you have to reduce energy. Nobody has seriously gone down the perfectly possible road of using .32ACP instead of 9x19mm and getting a lighter gun, lower recoil and more ammunition carriage on the soldier because it will not reliably stop the naughty enemy soldier nor poke a big enough hole in him. In a pistol the .32ACP lighter recoil allows the less experienced or smaller shooter to more easily handle his gun and place his rounds. Rather as the Enfield .38-200 revolver did when it replaced the .455" Webley which overwhelmed the inexperienced normal user. As a PDW at close I can see a small 32ACP machine carbine in that role but not as a weapon to dominate out to 200 metres.

 

[SaparotRob]

Thirty aught six or death!

Mods, delete if too political.

 

[ThomasP]

Henri Delacre's mle 1936. A bullpup design in 9x19 Parabellum. 32-round magazine, ROF of 500 rpm, MV of 1250 ft/sec, 8.75 lbs loaded.

I cannot see any reason why a similar design could not accommodate a more powerful cartridge.

 

[marathag]

I cannot see any reason why a similar design could not accommodate a more powerful cartridge.

Simple blowback, you need a Big heavy bolt to work when going from a low power cartridge to a higher one
One of the few successful powerful blowback carbines firing a intermediate class round was the Winchester 351 and 401 SelfLoaders that had 1900J and 2700J energy
the 401SL weighed 9 pounds when it flush magazine was loaded

both saw very limited use in WWI.

Back to this bullpup. It's obviously not blowback. Some kind of locked breech with a cartridge lifter to get it to the bore axis
I don't see how cartridges from the magazine get to the chamber, at 500rpm reliably
I don't believe this design ever got past paper

 

[ThomasP]

I do not know how practical the particular design was, but it illustrates the fact that the bullpup SMG concept existed pre-WWII. I cannot think of any reason why it could not have been easily adapted/developed to meet the criteria of this thread.

??

 

[z42]

In 1944 the British army was considering [...] moving infantry rifles and LMGs to 7.92mm Mauser.

Wait, what? What problem would this have solved vs keeping the .303?

 

[yulzari]

Wait, what? What problem would this have solved vs keeping the .303?

They wanted a semi automatic standard infantry rifle and .303 rimmed was not a sound choice for that task and they were familiar with 7.92mm Mauser and were already making the ammunition for the armoured regiments. Indeed Inglis was making the Bren in 7.92mm Mauser in quantity for the Chinese and the RAC were asking if they could swap their .303" Brens for Chinese style guns to use the same ammunition as their BESA machine guns on the tanks and armoured cars.

It was a faster, simpler and low risk way to move away from the bolt action rifle to a modern semi automatic one. The supporting Bren guns could be modified with new barrels. The SLEM was experimentally made in Britain during the war in 7.92 Mauser and went back to FN in Belgium and returned ten years later as the L1A1 in 7.62x51 NATO and the Bren became the L7 for the same ammunition so it sort of did happen that way but there was the whole Rifle no9 saga in between.

 

[yulzari]

Thirty aught six or death!

Mods, delete if too political.

Death it is then. Quick and painless or slow and painful? (see Futurama)

 

[Shortround6]

One must consider what is 'better' about smaller diameter faster cartridges. The purpose of the machine carbine is to dominate the gap between pistol arms length/pointy stick range and LMG fire range in a portable cheap small firearm. Say 25 metres to 200 metres. Beyond that you use an LMG and standard infantry rifle. If naughty chappie is over 200 metres away stop firing at him with a machine carbine as you will annoy him and draw his fire. Call upon your crew automatic weapon to make him stop it and go away.

The target remains the same and needs a certain amount of energy transferred to poke enough hole into it. To reduce weight you have to reduce energy. Nobody has seriously gone down the perfectly possible road of using .32ACP instead of 9x19mm and getting a lighter gun, lower recoil and more ammunition carriage on the soldier because it will not reliably stop the naughty enemy soldier nor poke a big enough hole in him. In a pistol the .32ACP lighter recoil allows the less experienced or smaller shooter to more easily handle his gun and place his rounds. Rather as the Enfield .38-200 revolver did when it replaced the .455" Webley which overwhelmed the inexperienced normal user. As a PDW at close I can see a small 32ACP machine carbine in that role but not as a weapon to dominate out to 200 metres.

We have 3 classes of weapons possible and 3 classes of cartridges, with some overlap.
We have the locked breech-guns, higher powered and expensive to built. (few, if any guns built?)
We have the delayed blow back guns, a bit lower powered and a bit cheaper.
We have the blow back guns which fall into two sub categories. The Pre-WW II gun maker style (still expensive) and the stamped (or tube) steel el cheapo's that showed up very quickly.
In the 1930s there was some argument over which direction to take. Including the Czech ZK-383

Which not only had the bi-pod but had a quick change barrel. Also had a detachable bolt weight to change the rate of fire, but you had to take the gun apart to do it.
There were several guns operating as delayed blowbacks, usually for the 9mm Mauser export cartridge. The delayed blow back guns generally had a slower rate of fire than the straight blowback guns. BTW the Thompson gun was supposed to be delayed blowback but they found they could leave the locking piece out with hardly a change in rate of fire and the bulk of the war time guns used the simpler blowback set up.
The French went the other way

using the 7.65 Longue and it was only long in comparison to the 7.63 APC. The gun only weighed about 6.3lbs despite being made of machined steel.
With on of the two lowest powered rounds used in submachine guns in WW II the light weight was not a problem.
Many of the 1930s (and earlier) guns had very optimistic sights.

Without getting into the area of intermediate rifle cartridges (7.9 x 33 mm German) the 9mm Mauser was about as powerful as guns got. Around 1360fps with a 128 grain bullet for about 530ft/lbs muzzle energy. (pistol ballistics)
Perhaps the US could have made a rimless .357 magnum for submachine gun use (9 X 33mm) with a straight case but it would only gain 100-200fps over the longer 9mm rounds already in use. And a blowback .357 mag gets a little scary.

as far as a "smaller" cartridge goes the late 50s (or 1960) they tried necking the .357 mag down to .257 (called the .256 Winchester Mag) and got 2200fp out of an 8 1/2in barrel using a 60 grain bullet. But you still need a .357 mag size action and you still need the long case so all you have lose is some bullet weight.
Note that this gets you about 200fpm more than the M 1 carbine with a bullet of almost 1/2 the weight, granted a shorter barrel on the Carbine will have some velocity loss.
These short barreled high pressure cartridges have more muzzle flash and muzzle blast than the standard 9mm rounds.

The 7.63 Mauser and 7.62 Torkarev were pretty much necked down 9mm Mauser.

I am not seeing any significant advantage to the smaller diameter bullets in a submachine gun. Not saying there isn't any, but adding 20-40 meters of range to a 150-200 meter gun may not have been worthwhile?

 

[tomo pauk]

as far as a "smaller" cartridge goes the late 50s (or 1960) they tried necking the .357 mag down to .257 (called the .256 Winchester Mag) and got 2200fp out of an 8 1/2in barrel using a 60 grain bullet. But you still need a .357 mag size action and you still need the long case so all you have lose is some bullet weight.
Note that this gets you about 200fpm more than the M 1 carbine with a bullet of almost 1/2 the weight, granted a shorter barrel on the Carbine will have some velocity loss.
These short barreled high pressure cartridges have more muzzle flash and muzzle blast than the standard 9mm rounds.

Make the .256 WM as a rimless round and it is perfect as a Carbine round, ie. for a weapon that can be very light and handy while being with the locked bolt action.
Necking down the .38 Super to 6.35-6.5mm would've produced a less violent cartridge, but still with very good ballistics, and that can be used in pistols. Same for the 7.62 Tokarev, or the 9mm Mauser Export/7.63 Mauser.

 

[marathag]

se at long range (much over 100 yds) requires skill, good sights and quite possibly an observer.

Have fired a Thompson at 200 yard range, with the ladder sight
Yes, with a 30 round mag, you can walk the rounds onto the target before the mag is empty.

The Thompson had terrible recoil, really have to wrestle with it to keep on target, and the Cutts muzzle brake hardly helping.
In comparison, doing the same with an M2 Carbine was a snap

 

[Shortround6]

There is more to making a 100-300 meter "carbine" than just the cartridge.
Shootability helps, a lot.
Crappy triggers, Crappy sights (hard to see), hard to hold and so on.
A lot of the 1920s/1930s guns were too expensive but a lot of the war time guns were too cheap.
One Soviet model didn't have a safety, it relied on a very, very heavy trigger pull. Cheap but rather limits the accuracy of the users even more than most Military guns.
Having no way to zero the guns (sights are welded in place) just means most men can can only point in the general direction of the enemy. OK at short ranges (rock throwing) but not so good at even 100 meters. Unit armorers should have a way to move the front sight left and right and perhaps change the sight out for different height ones to zero the basic gun. Damaged/bent guns can be repaired vs replaced?
Getting the shooters eye behind the sight easily is important. Too awkward and the shooter will simply look over the sights. Having rods poking out the back or trying to force the cheek down on steel tube (or bent wire) in order to see through the sight are somewhat self defeating.

Some officers (on weapon selection committees) had a rather low opinion of troops in general and their ability to be trained to use things much more complicated than a rock (may say something about the training methods rather than the troops). Since they couldn't train the troops anyway just give them bullet squirters. Saves time for important training like close order drill

 

[peceed]

The biggest ww2 "missed opportunity" for "heavy smg"/"proto-assault riffle" is Thompson 0.30 Carabine.

 

[SaparotRob]

It would've been the coolest looking one.

 

[tomo pauk]

Interesting tidbit can be read on Wikipedia:
Barrel production was often simplified by using barrels for the 7.62mm Mosin–Nagant: the rifle barrel was cut in half and two PPSh barrels were made from it after machining the chamber for the 7.62×25mm Tokarev cartridge.[21]​

Japanese doing the same, or perhaps even cutting the old, long barrels to 3 pieces for their 6.5mm SMG cartrridge might've increased their production of SMGs by a good margin.​
(yes, Japanese still loose the war)​

 

[Shortround6]

Interesting tidbit can be read on Wikipedia:
Barrel production was often simplified by using barrels for the 7.62mm Mosin–Nagant: the rifle barrel was cut in half and two PPSh barrels were made from it after machining the chamber for the 7.62×25mm Tokarev cartridge.[21]​

Japanese doing the same, or perhaps even cutting the old, long barrels to 3 pieces for their 6.5mm SMG cartrridge might've increased their production of SMGs by a good margin.​
(yes, Japanese still loose the war)​

Barrel manufacture was not the real sticking point.
And ease of barrel manufacture at the cost of a new cartridge is not going to really help things.
early version/s of the Japanese SMG were overly complicated.

But it was the lack of contracts and lack of perceived need until much to late that were the real problems.
And you often CANNOT take old rifle barrels and cut them up. You can take new barrel blanks (rifled tubes not yet machined on the out side) and cut them into parts.

Barrel for PPSh 41. You need the ring and short collar for mounting into the gun. You could use a two piece (collar and barrel tube) but that is more time/machining.
For the Soviets, did they have the needed diameter 300mm out the barrel on an existing barrel? Remember that you have to cut about 54mm off the breech end of the existing barrel to rid of the 7.62 x 54 chamber and what is the diameter of the existing rifle barrels that far out?
Barrel blanks are easy.

For the Japanese in 1939-39. Decide that you are going to actually use submachine guns. Lengthen the 8mm Nambu out another 3-4mm (won't fit in old pistols), use 7.7 bullets and barrels. Use two position flip sight at the rear. Forget bipod and bayonet.

 

[tomo pauk]

early version/s of the Japanese SMG were overly complicated.
But it was the lack of contracts and lack of perceived need until much to late that were the real problems.

Agreed all the way.

And ease of barrel manufacture at the cost of a new cartridge is not going to really help things.

If the old cartridge is anemic, the new cartridge is needed anyway. The 'no free lunch' rule applies.

And you often CANNOT take old rifle barrels and cut them up.

Yes, if there is no old barrels, you can't do anything with them.

For the Japanese in 1939-39. Decide that you are going to actually use submachine guns. Lengthen the 8mm Nambu out another 3-4mm (won't fit in old pistols), use 7.7 bullets and barrels. Use two position flip sight at the rear. Forget bipod and bayonet.

Agreed pretty much. The 7.7x25mm has a nice ring to it.
Pistols, especially old and/or weak, are not an issue anyway, being the least important among the small arms.