What If: World War II SHTF automatic carbines/rifles (3 Viewers)

[BarnOwlLover]

This is for if a semi-auto carbine or even a select fire machine carbine/automatic carbine/automatic rifle (remember, the term assault rifle/strumgewher hasn't been invented until 1944 reportedly), and I know that even for infantry weapons a lot changed between 1939 and 1945. This applies to both Allies and Axis, though for Germany late war assault rifle development is fairly well documented and is thus not a huge "what if" unless we get into speculation like what I'm posing here.

But let's say that one, the Germans took the assault rifle concept more seriously earlier in the war, and that the Allies (namely western Allies) took it seriously as well. But what's desired is a cheap, simple carbine/assault rifle that can be made on basic tooling and machinery, so stampings and minimal machine time are the word of the day.

There was a rifle that FN started working on in the late 1940s that supposidly was some kind of proof of concept weapon or an R&D project. I has a few elements that were on the FN Universal Carbine (forerunner to the FN FAL) and even the FAL itself, but not many. This weapon was made mostly out of stampings, and used a rear-locking rotating bolt. Only one has been confirmed to exist, and is currently keep in FN"s historical collection at their main plant in Herstal, Belgium:

Historical Firearms - FN’s .30 Carbine Prototype In 1946 Dieudonne...

FN’s .30 Carbine Prototype In 1946 Dieudonne Saive, newly returned from Britain, resumed his work at FN developing his self-loading rifle design (previously known as the EXP-1 while in development in Britain) which would become the FN Model 1949. At the same time Saive and his team, Groupe 74...

www.historicalfirearms.info

But if we want to take somewhat more "modern" rifles built along the lines I laid out above, there's the Armalite AR-18/-180:

ArmaLite AR-18 - Wikipedia

en.wikipedia.org

And the even allegedly simpler SAR-80 and Leader Dynamics T2, which are modified AR-18 derivatives:

SAR 80 - Wikipedia

en.wikipedia.org

Leader Dynamics Series T2 MK5 - Wikipedia

en.wikipedia.org

Now, going back to World War II, what changes would/should be made to make any of these weapons viable (like for instance, I know that polymer wasn't a huge thing back then, so things like stocks and handguards would have to be likely made out of wood or sheet metal)? Also, unless you want to play the SCHV (Small Caliber, High Velocity) intermediate rifle round card 15-20 or so years early, what caliber should they be made in given the time, such as things that were available back then (.30 Carbine, 7.92x33mm Short/Kurz, .351 Winchester SL, for example) or something original or obscure, or even later, up to I guess .30 Carbine being necked down to .22 caliber (which was done I believe shortly after the Korean War first at the Aberdeen Proving Grounds in a M2 Carbine, as well as when Melvin Johnson created the 5.7mm MMJ/.22 Spitfire round for M1/M2 Carbine type weapons).

 

[tomo pauk]

The .351 necked down to .25 would've been just fine, IMO. The 'metric' people might've opted for a shortened 6.5mm catridge, something like 6.5x35 to x40.
A more adventurous .30 Carbine that is made to be close to the Soviet 7.62x39 would've worked great, too.
The .25 Remington, but a bit shortened and hotter loaded should've also been good IMO.

Also, unless you want to play the SCHV (Small Caliber, High Velocity) intermediate rifle round card 15-20 or so years early,

Interestingly enough, the .22 calibre was popular in many countries for the training rifles, meaning that the bore making tooling is available. So up the game, and make a more substantial cartridge than the .22 LR was, and there it is.

 

[BarnOwlLover]

Or how about (though we may be crossing into non-SHTF territory--I'll explain) something like a Beretta AR70 or AR70/90, or a Sig 540 or 550? Not as crude as the other examples that I mentioned, and def. less cheap and crude feeling. And though the Beretta AR70 was far cheaper to make than say an AR-15 back in the early 1970s for those who didn't have CNC machines and not accustomed to working with aluminum forgings, it was more durable and substantive than the AR-18 and many of it's derivatives (though the SAR-80 doesn't seem as cheap or crude as the AR-18 or the T2). But it's probably a fair bit more expensive than say the AR-18/T2.

But then again, one of the reasons it seems that the AR-18 didn't find favor with the US Army during Vietnam, in addition to the AR-15/M16 getting most of it's bugs worked out by the time the AR-18 was ready, was that the AR-18 was probably deemed too cheap and nasty, much like the British Army with the Sten SMG during World War II.

And with the Sig 540 and 550, well, it's still Swiss, and cheap for the Swiss often means well above average price for many others. I didn't include the newer (recently launched) Sig 560 rifles, since those have aluminum lower receivers I think, and that's a tech that's a bit out there for World War II.

 

[tomo pauk]

IMO, keeping with the basic StG-44 design would've been both affordable and would've gave a very good weapon. Or, if the cartridge selected is a bit weaker, the M1 Carbine design and go from there.

 

[Shortround6]

Different countries had different abilities to make stamped sheet metal guns.
Most countries could make stamped sheet metal (or steel tubing) blow-back submachine guns.
The Problem was scaling them up to take higher powered ammunition.
You could make sort of a super 9mm (like a 9mm Mauser export or a 9 X 23/25 mm).
You need a heavier bolt and/or stronger recoil spring.
Once you start getting into a locked breech you need a lot more machining and tighter tolerances.
The AR gets away with an Aluminum receiver (or sheet metal AR-180) because the receiver doesn't handle the strain of firing, unlike most bolt action rifles or the the US M-1/M-1 carbine.

This is the barrel extension for an AR-15. The actual barrel screws into the threads. The bolt locks into the locking recesses. The aluminum or sheet metal receiver just held everything in alignment. In the US M-1s (both) the barrel screwed into the receiver and the bolt locked into the locking recesses in the receiver.

A lot of the assault rifle cartridges use smaller cartridge that full power rifles BUT the cartridges often operate at pressures that are just as high or close.

Now in WW II how good was the ability of a particular country to make a strong, durable sheet metal receiver that could precisely hold all the needed parts in alignment?
Submachine gun just needed the bolt to go back and forth. No twisting or turning or tipping up or down. Later submachine guns didn't even have a firing pin. They just machined a lump on the face of the bolt and the gun fired when the cartridge was jammed into the end of the chamber and stopped while the bolt traveled that short distance further to crush the cap.

Maybe the Soviets and the Japanese cared about the bore size of their guns to save tooling. Most other large countries did not. The bore drills, reamers and rifling cutters all wear out and need to be replaced parodically. If your machine tool industry is up to snuff, they can make what you want.
The other side is manufacturing the ammunition. And at some point somebody has to decide if a smaller diameter bullet takes less raw material and the savings pays for the changes in tooling. You can use a lot but not all of the tooling to make a short 7.9mm bullet compared to a long 7.9mm bullet. But even steel dies working copper alloy jackets will wear (slowly) and need to be replaced.

 

[z42]

One possibility if the butterflies had flapped their wings slightly differently would be the US army adopting the M1 Garand in .276 Pedersen.

Add in a box magazine and you could have something assault rifle-like already in service before the war breaks out.

 

[Shortround6]

French 1918 prototype

25 round magazine in 8 X 35 mm (necked down .351 Winchester?)
Pure blowback and as a result the gun, empty, weighed 5.1kg. It also had a MV of 570m/s which means a shorter than desired combat range for a rifle.
If you use a locked breech the cost of the gun (due to machining) goes up and the weight of the gun (lighter bolt, spring and receiver) goes down.
Where you are as far as raw material goes ????

You still need a full power LMG in the squad or at least several in a MG section in the platoon. Unless you KNOW that that you will not be operating in open spaces.

 

[Frog]

French 1918 prototype
View attachment 815488
25 round magazine in 8 X 35 mm (necked down .351 Winchester?)
Pure blowback and as a result the gun, empty, weighed 5.1kg. It also had a MV of 570m/s which means a shorter than desired combat range for a rifle.
If you use a locked breech the cost of the gun (due to machining) goes up and the weight of the gun (lighter bolt, spring and receiver) goes down.
Where you are as far as raw material goes ????

You still need a full power LMG in the squad or at least several in a MG section in the platoon. Unless you KNOW that that you will not be operating in open spaces.

The 8 X 35 SR for this Ribeyrolles M1918 prototype was a neck down Winchester .351 SL case with the same 8 mm ball as for the Lebel rifle. The .351 and .401 SL were known to the French Ordance as these Winchester carbines were used by the French air Force.

 

[Frog]

Different countries had different abilities to make stamped sheet metal guns.
Most countries could make stamped sheet metal (or steel tubing) blow-back submachine guns.
The Problem was scaling them up to take higher powered ammunition.
You could make sort of a super 9mm (like a 9mm Mauser export or a 9 X 23/25 mm).
You need a heavier bolt and/or stronger recoil spring.
Once you start getting into a locked breech you need a lot more machining and tighter tolerances.
The AR gets away with an Aluminum receiver (or sheet metal AR-180) because the receiver doesn't handle the strain of firing, unlike most bolt action rifles or the the US M-1/M-1 carbine.
View attachment 815463
This is the barrel extension for an AR-15. The actual barrel screws into the threads. The bolt locks into the locking recesses. The aluminum or sheet metal receiver just held everything in alignment. In the US M-1s (both) the barrel screwed into the receiver and the bolt locked into the locking recesses in the receiver.

A lot of the assault rifle cartridges use smaller cartridge that full power rifles BUT the cartridges often operate at pressures that are just as high or close.

Now in WW II how good was the ability of a particular country to make a strong, durable sheet metal receiver that could precisely hold all the needed parts in alignment?
Submachine gun just needed the bolt to go back and forth. No twisting or turning or tipping up or down. Later submachine guns didn't even have a firing pin. They just machined a lump on the face of the bolt and the gun fired when the cartridge was jammed into the end of the chamber and stopped while the bolt traveled that short distance further to crush the cap.

Maybe the Soviets and the Japanese cared about the bore size of their guns to save tooling. Most other large countries did not. The bore drills, reamers and rifling cutters all wear out and need to be replaced parodically. If your machine tool industry is up to snuff, they can make what you want.
The other side is manufacturing the ammunition. And at some point somebody has to decide if a smaller diameter bullet takes less raw material and the savings pays for the changes in tooling. You can use a lot but not all of the tooling to make a short 7.9mm bullet compared to a long 7.9mm bullet. But even steel dies working copper alloy jackets will wear (slowly) and need to be replaced.

As a cheap US contender : the T29 adaptation of the M3 SMG to fire the .30 carbine round with a longer barrel.

 

[BarnOwlLover]

One could go as far as to say why not use select fire versions of the Remington Model 8 or 81 (81s were made with detachable mags) in something less powerful than .30 Remington (basically an auto-loading equivalent to .30-30 Winchester in dimensions and power), or even select fire, extended mag versions of the Winchester M1907 or even M1910. Though I'd argue that maybe .401 WSL is a bit too much for an intermediate round (not ballistically, but it's bullet is pretty heavy). It's been alleged that some 1907s were made to be select fire for the French during World War I (though never officially verified).

Of course, it's been commonly said that 7.62x39mm produces ballistics similar to .30 Remington or .30-30. And the same has been said at times of the .351 WSL. I've also seen arguments that the M1 and especially M2 carbines were early assault rifles. Well, not really, if we take into account of most standards such as what NATO uses, which are based on the US Army's definition there of, where the main features are:

1: Select fire (semi and full auto)
2: Fires a round less powerful than a full power rifle round and more powerful than a pistol or PDW round (stuff like the 4.6x30mm HK or the 5.7x28mm FN)
3: Has an effective range of at least 300 yards or meters.

The M1 is semi-auto only, and the M2 may be select fire, but both carbines have an effective range of only about 200 yards. I sort of doubt that the .22 Spitfire has much more range than .30 Carbine, given that Johnson marketed rifles that fired it as short range hunting rifles and survival rifles.

Granted, rounds like the .32 WSL (which inspired the .30 Carbine) and .35 WSL were even worse than .30 Carbine as far as being assault rifle rounds. Not to mention the whole US carbine program was for basically a PDW rather than an "assault rifle".

As far as things like the StG 44 and the M1/M2 carbines suggested above, the Germans were looking for something for something cheaper, simpler and lighter than the StG 44. The StG 44 weighed more than the Thompson SMG, and quite a bit more than the M1 Garand. The result was the Mauser Gerat 06/06H, which became famous as the forerunner to the HK G3 and CETME rifles (though the latter 2 fired much more powerful rounds than the StG 45--7.62mm NATO/.308 Win. vs 7.92x33mm). Granted, though the StG 45 was way cheaper than the StG 44 (which is why the Germans were looking at it as at least a substitute standard issue rifle to be issued and built along side the StG 44).

However, ironically, both the FN FAL (which used a forged receiver assembly and a rear-locking tilting bolt) and the HK G3 and especially the G41 (NATO-spec HK33, basically a scaled down 5.56mm G3, all of which ware roller-delayed blowback) were ultimately determined to be too expensive to mass produce down the road. Hence FN designed the CAL (mostly stamped, but a complicated bolt system) and FNC (stamped upper, forged aluminum lower, used a modified AK-bolt) and HK designed the G36 (mostly polymer receiver, AR-18 inspired bolt and gas system). Of course, the FNC's lower (forged aluminum) and the G36 (polymer receiver) aren't really practical for World War II production.

But I guess that I'm asking do we need a true SHTF rifle that's ultra crude to make (like the AR-18 was originally), or something simple but more substantive (Beretta AR70)? Mind you, it also probably depends on how things are going as well (desperate times, or needing/wanting a simple weapon to keep up with wastage and losses, but still be decent for say maybe post war use at least short term).

 

[tomo pauk]

Is there anything wrong with the M1 Carbine design that picked up a kilo (~2 lbs) in order to fire more powerful .30 round than it is the .30 carbine?

 

[Shortround6]

from original post.

But what's desired is a cheap, simple carbine/assault rifle that can be made on basic tooling and machinery, so stampings and minimal machine time are the word of the day.

When you get into locked breech guns and gas systems (like even the M-1 carbine) the cheap and simple starts to go away. It may be a better gun or a better weapon than a machined bolt action rifle but it is not going to be a cheap, high power Sten gun.

Stampings can cheap, but that often means uncomplicated or needed further 'assembly' or both.

Part of a US M3 Grease gun. Note the combination of welding and riveting. They could be cheap to produce but all of the parts could not be made in small machine shops in garages.
A lot of parts could but not all.

I would also note that the older American commercial guns, the Remington and the Winchesters were not popular because of their recoil. They were also not light. The Remingtons were recoil operated and the barrel moved inside the outer shroud. A lot of weight moving around from shot to shot. The Winchesters used a huge weight hiding in the forend attached to bolt to keep the bolt closed until the pressure dropped. Large weight is cheap.
Light weight and cheap are often in conflict.

My father once worked on a project at Colt for a belt feed grenade launcher with a stamped sheet metal receiver. He was a production engineer (figure out how to make what the gun designers drew up). I don't know how it worked out but they were having trouble spot welding the guide rails into the receiver. The heat of the spot welding warped the guide rails and made them go out of spec/tolerance. Slightly bent guide rails means jams.
You can often farm out (subcontract) parts and assemblies, but you need really good engineering to start with for everything to fit together at final assembley.