What-if SMG for late 1930s and on

A very prominent and sometimes 'fancy' weapon in the ww2, SMGs came in many layouts and in a number of cartridges. Some were better than others, some offering the 200m efficient range vs. others with 150 or even 100m (although the metrics of deciding the exact effective range seem lacking). Some started with drum magazines, by the end of ww2 most were using 'stick' magazines, again some mags being better than other.

So - let's 'make' as good SMG as possible. Either a mod of OTL weapon, or something that emerged after ww2. Cartridge choice - anything plausible for technology of ww2, no need to stick with what was available in a specific country back then. Size, weight, RoF are important, so is reliability and suitability for mass production. It will be good if effective range should come close to 200m, although 150m seems like a good average so we don't over-stretch the barrel. A 'simple blowback' operation, as it was the case with the SMGs of the day that mattered (keeps the wepon simpe and cheap; does not work well with cartridges like it was the .30 Carbine or 'stronger').
 
A very prominent and sometimes 'fancy' weapon in the ww2, SMGs came in many layouts and in a number of cartridges. Some were better than others, some offering the 200m efficient range vs. others with 150 or even 100m (although the metrics of deciding the exact effective range seem lacking). Some started with drum magazines, by the end of ww2 most were using 'stick' magazines, again some mags being better than other.

So - let's 'make' as good SMG as possible. Either a mod of OTL weapon, or something that emerged after ww2. Cartridge choice - anything plausible for technology of ww2, no need to stick with what was available in a specific country back then. Size, weight, RoF are important, so is reliability and suitability for mass production. It will be good if effective range should come close to 200m, although 150m seems like a good average so we don't over-stretch the barrel. A 'simple blowback' operation, as it was the case with the SMGs of the day that mattered (keeps the wepon simpe and cheap; does not work well with cartridges like it was the .30 Carbine or 'stronger').
My $.02 worth. A two or more track approach might be helpful. I see several different directions one could take:

ie.
-A simple blow back full auto only SMG (probably using advance primer ignition with a fixed firing pin ?)
-A more complicated selective fire SMG that fired from a closed bolt.

-In terms of cartridges using common pistol cartridges may have certain advantages, but on the other hand an optimized SMG cartridge might also be useful.

-In terms of rate of fire, a slow cyclic rate might be helpful in some circumstances, or a faster cyclic rate (perhaps combined with a 3 round burst fire mode ?) might be helpful in others.

As a general comment devising reliable box magazines would likely be helpful.

As a general comment devising highly reliable safety mechanisms would seem helpful to me.

I suppose one needs to decide what one wants (ie. a weapon for relatively well trained specialists, something for mass issue to poorly trained hastily mobilized militia, something to be used in place of a service rifle, something for non combat troops to carry "just in case" etc.)

Hope that is of some interest :)
 
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I'd stick with stick magazines :) Hopefully, double-row double-feed flavor for better reliability and ease of loading of the mags.
The SMGs, even the best, were not a suitable replacement for rifles in all tasks? Unless one has bad rifles, of course.
The 'dedicated' round might be a worthwhile proposal. The SMGs will be going through bullets' stock like it's nobody's business anyway, the legacy cartridges might put the unnecessary brakes on SMG's potential. Americans might use the rimless version of the .38 Super (1200-1400 m/s) instead of the .45 ACP (830-1100 m/s) for better trajectories? Or perhaps a shortened & rim-less .32 WSL, making ~650-700J instead of 950+?
This might also be suitable for Germans, diameter of the bullet is as close as possible to the 8mm Mauser.
 
Winchester 1907 in .351SL, but double stack magazine, Shorter barrel and pistol grip.
More powerful than 9mm or .45, but not so much that was uncontrollable in FA, as the French found in WWI.
 
Winchester 1907 in .351SL, but double stack magazine, Shorter barrel and pistol grip.
More powerful than 9mm or .45, but not so much that was uncontrollable in FA, as the French found in WWI.

Americans have had an assault rifle in production back in ww1 without knowing it...
 
Americans have had an assault rifle in production back in ww1 without knowing it...
It was called the Burton Light Rifle. Two magazines, designed for rapid interchangeability when one ran out of ammunition, selective fire by seperate trigger, 1917-ish. Designed for use in biplanes if memory serves.
 

??

It was called the Burton Light Rifle. Two magazines, designed for rapid interchangeability when one ran out of ammunition, selective fire by seperate trigger, 1917-ish. Designed for use in biplanes if memory serves.

Winchester's gun was in production & use, Burton's weapon remained in prototype stage.

For the Italians and perhaps Japanese: 6.5mm x 25, ie. the 7.62x25 necked down? Barrel-making should be easier than going for 9mm. Ammo fired by a simple blowback SMG.
 
Thoughts:

Use a Russian 7.62 x 25mm round. Have 25 round stick magazines, 50 round drum magazines, and a 75-to-100 round Big Drum magazine. Have either single fire or a rate of fire such that single fire is realistic with a quick trigger pull. Mechanically, keep it simple - open bolt, simple dust cover that can double as safety, stamped sheet metal construction, and easily mass-produced. If desired make a carbine version with a longer barrel for longer range akin to a small M1 carbine.
 

If we're going to make the optimal SMG why not draw from historical examples to improve upon? What did they do well? What did they not do well?

Winchester's gun was in production & use, Burton's weapon remained in prototype stage.

For the Italians and perhaps Japanese: 6.5mm x 25, ie. the 7.62x25 necked down? Barrel-making should be easier than going for 9mm. Ammo fired by a simple blowback SMG.

Point noted, but why neck down the 7.62 x 25mm cartridge? To get the desired effects it's still among the best cartridges available.
 
If we're going to make the optimal SMG why not draw from historical examples to improve upon? What did they do well? What did they not do well?

Okay, that's fair.

Point noted, but why neck down the 7.62 x 25mm cartridge? To get the desired effects it's still among the best cartridges available.

Both of these countries have the machines for making the 6.5mm barrels, that should speed up the series production of SMGs in that calibre. The 6.5mm bullet fired by what was used to fire 7.62mm bullets will gain speed, compensating for lower mass of bullet.
Both counties also might go to 8mm for the same manufacturing reasons (Japanese actually did it), but with something much more potent than the 8mm Nambu or .32 ACP.

Doh - both countries were also making the 7.7mm weapons - looks like I can't make any excuses for them not going the 7.62x25 way :)
 
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Both of these countries have the machines for making the 6.5mm barrels, that should speed up the series production of SMGs in that calibre. The 6.5mm bullet fired by what was used to fire 7.62mm bullets will gain speed, compensating for lower mass of bullet.
Both counties also might go to 8mm for the same manufacturing reasons (Japanese actually did it), but with something much more potent than the 8mm Nambu or .32 ACP.

Doh - both countries were also making the 7.7mm weapons - looks like I can't make any excuses for them not going the 7.62x25 way :)

Why not both...?

Dumb question- Would it be feasible to make an SMG with modular barrels and magazine adapters en masse to accomodate 6.5x25mm, 7.62x25mm, and 9x19mm ammunition?
 
Select fire Sterling SMG in 9x25mm 'Imperial' - this is a modernised version of the 9x25mm Mauser cartridge but 'hotter' with a bullet optimised for higher velocity

Basically 'The OTL Sterling' but not wedded to the 9x19mm Para and the need to be backwards compatible with STEN gun magazines

The 9x25mm Imperial is slightly lighter than 9mmx25 Mauser at 7 grams or 108 grains (verses 8 grams or 125 grains for the German round) and better optimised for velocity than the OTL parent round.

(In layman's terms it is more pointy)

Using the hotter loads of the day the round has a 424-450 Meters Per second MV with an energy of about 700-750 Joule (515-550 Ft/Pounds)

(the above is completely made up based on OTL 9x25mm and 7.62x25mm)

Fairy Dust powered Travellers from our TL will notice the much longer barrel of the Sterling over the OTL one - this was to make better use of the more powerful cartridge to increase accuracy and effective range

Note the short tank crew version (often equipped with a shorter 16 round magazine but compatible with the 34 round standard magazine)


sterling_pair_001.jpg
 

Driftless

Donor
Might the two-track idea come from two different mission profiles? A more sophisticated version for use by assault forces, and a down-and-dirty version for secondary users (tankers, artillery, rear echelon, etc)
 

CalBear

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A very prominent and sometimes 'fancy' weapon in the ww2, SMGs came in many layouts and in a number of cartridges. Some were better than others, some offering the 200m efficient range vs. others with 150 or even 100m (although the metrics of deciding the exact effective range seem lacking). Some started with drum magazines, by the end of ww2 most were using 'stick' magazines, again some mags being better than other.

So - let's 'make' as good SMG as possible. Either a mod of OTL weapon, or something that emerged after ww2. Cartridge choice - anything plausible for technology of ww2, no need to stick with what was available in a specific country back then. Size, weight, RoF are important, so is reliability and suitability for mass production. It will be good if effective range should come close to 200m, although 150m seems like a good average so we don't over-stretch the barrel. A 'simple blowback' operation, as it was the case with the SMGs of the day that mattered (keeps the wepon simpe and cheap; does not work well with cartridges like it was the .30 Carbine or 'stronger').
That isn't a SMG. by definition. SMG use a pistol caliber round. They are designed for up-close and personal action. As an example, one of the most popular SMG rounds, the 9x19mm (9mm Lugar) has 1.8" drop from 25 to 50 yard (which is significant) and more than a FOOT at 100 yards.The 7.63mm (30 Mauser) is even worse while the .45 APC is slightly better at 50 yards, but the heavier round also suffers more as range increases. The .30 Carbine actually has better performance, but still quite weak, at any sort of range,

What you described is an assault rifle using something like the 7.62x39. Much better range and energy, but also a heavier weapon and heavier round (i.e. same number of rounds will weight much more than pistol rounds). There is also the small caliber, very high velocity option (5.56mm NATO or the 5.45mmx39 introduced by the Soviets)
 
That isn't a SMG. by definition. SMG use a pistol caliber round. They are designed for up-close and personal action. As an example, one of the most popular SMG rounds, the 9x19mm (9mm Lugar) has 1.8" drop from 25 to 50 yard (which is significant) and more than a FOOT at 100 yards.The 7.63mm (30 Mauser) is even worse while the .45 APC is slightly better at 50 yards, but the heavier round also suffers more as range increases. The .30 Carbine actually has better performance, but still quite weak, at any sort of range,

What you described is an assault rifle using something like the 7.62x39. Much better range and energy, but also a heavier weapon and heavier round (i.e. same number of rounds will weight much more than pistol rounds). There is also the small caliber, very high velocity option (5.56mm NATO or the 5.45mmx39 introduced by the Soviets)
So let's go with what worked. This SMG meets most if not all criteria desired.

 

CalBear

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So let's go with what worked. This SMG meets most if not all criteria desired.

That isn't an effective range for aimed fire, it is the lethal range, which, to be fair is what a SMG is all about, Spray & Pray. At 150 meters the 7.63 (30 Mauser) has a bullet drop approaching a meter. You will find the same effective range figure for the Thompson. If someone hits a man sized target firing a single round from a Thompson (and it actually can be done if you memorize the ballistic tables) they are also the guy getting 1,500 yard hits with a .30-06 (the bullet drop for a .30-06 at 1,500 yards (a .30-06 round drops about 90 feet at that range, so you need to aim 90 feet above the target to hit it, it can be done, just not by the vast majority of shooters). Might find two of those guys in a Battalion.
 
That isn't an effective range for aimed fire, it is the lethal range, which, to be fair is what a SMG is all about, Spray & Pray. At 150 meters the 7.63 (30 Mauser) has a bullet drop approaching a meter. You will find the same effective range figure for the Thompson. If someone hits a man sized target firing a single round from a Thompson (and it actually can be done if you memorize the ballistic tables) they are also the guy getting 1,500 yard hits with a .30-06 (the bullet drop for a .30-06 at 1,500 yards (a .30-06 round drops about 90 feet at that range, so you need to aim 90 feet above the target to hit it, it can be done, just not by the vast majority of shooters). Might find two of those guys in a Battalion.
So 7.63 x 25mm is one thing, 7.62 x 25mm is *very* different. This SMG in 7.62 x 25 had a range if approx. 150m to 200m and seems to have served the USSR well, it might be a good place to start for a universal SMG
 
So 7.63 x 25mm is one thing, 7.62 x 25mm is *very* different. This SMG in 7.62 x 25 had a range if approx. 150m to 200m and seems to have served the USSR well, it might be a good place to start for a universal SMG
The OP also indicated that post ww2 developments could be taken advantage of, so I suppose a something along the lines of the MP5 firing an optimized cartridge, used by well trained soldiers who perhaps could be expected to deal with adjusting a sight for use beyond say 100 meters (perhaps often but not always in semi auto ?) is a possibility. On the other hand something along the lines of an Uzi or a Sterling might also be attractive to some.

I suppose if modern tech is some how made available then something with an action along the lines of the G11 or perhaps the AN94 that could fire short bursts at a very high cyclic rate with a single recoil impulse (to the operator) might have a niche role in WW2 and could be technically considered to be an SMG if it fired suitable ammunition.

I realize that assault rifles firing intermediate cartridges are probably a better investment for most nations than expensive optimized SMG's, but this thread is about optimized SMGs :)
 
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