3.5lb carbine requirement instead of 5lb?

sonofpegasus

The Mac 9 weighed 3.5lb IIRC, a longer barrel will add to that but it gives yuo and idea of what might be possible.
Would it be any good is a whole different question.
 

yulzari1

I do understand that 3.5lbs is the OP decision and the question is how it might be achieved but I am puzzled as to why such a demanding weight would be chosen. The weapon is for the defence of non front line personnel and a better PDW than a pistol whilst being easier to carry about than a short rifle. However, such troops are not carrying it about all the time. Often stowed or just lying nearby. Weight is not so critical as it would be for an infantry weapon. A danger is that inadequately rugged opponents will be incorporated.

It will be grossly abused and neglected by it’s users and has to stand up to that. Second
line troops notoriously neglect their weapons.

The Sten Gun came in at 7lbs and an M3 at 8lbs, so a half weight Sten Gun is questionable to my mind.
 
marathag

marathag

Banned
Ravinoff said:
s. Die-cast just tends to have problems with bubbles and other defects
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Really don't need Aerospace tolerances, or even Automotive level,, but STEN tolerances at minimum.
Still going to have a steel barrel and steel lower receiver. Stuff like grip housing and dust cover/upper can be magnesium alloy. Since this is a locked breech design, some of the bolt will be machined steel as well.
But the OPs goal was 3.5 pounds, and to get there, will need lightweight, but strong alloys.
As pointed out AL will be off limits, even though the expected AL shortages never came close to being a problem, even with over 100000 aircraft planned.
 
marathag

marathag

Banned
yulzari1 said:
It will be grossly abused and neglected by it’s users and has to stand up to that. Second
line troops notoriously neglect their weapons.

The Sten Gun came in at 7lbs and an M3 at 8lbs, so a half weight Sten Gun is questionable to my mind.
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Most of the weight was in the bolt. For a locked breech, you don't need that.
Now a massive bolt had a couple advantages.
Cheap and easy to make.
A secondary benefit was one that some guys I knew in West Germany took advantage of, when the M3 was their official Arm.
For long road marches, some of the guys would 'forget' to have the Bolt installed, and just carried a lightweight steel tube for the trip. All weapons were unloaded anyway, so not like there was any loss in combat abilities for those dumb marches.
 

Orcbuster

Magnesium would not be acceptable simply because it was not available in great quantities before the war and it was a strategic metal bottlenecked by production capacity during the war.

That and the pricepoint would be significantly raised.
 

tomo pauk

marathag said:
As with racing, lightweight costs more than heavy.
Contract is set for 3.5 lbs, and hard to get there without light alloys.
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You can note that the required effective range is 150-200 yds vs. what became the M1 carbine. That means the barrel can be half of the lenght of what M1 used - a weight saving. Reduce the use of wood as much as possible, replaced by plastic front stock and the wire buttstock - again reduces the weight. Receiver can be lighter, since a less powerful cartridge is sufficient (even the 7.62 Tokarev works here).
 

Peg Leg Pom

Job done with a pound to spare. Beef it up a bit to take 9 x 25mm and give it a longer barrel and it'll do nicely.

en.wikipedia.org

Škorpion - Wikipedia

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marathag

marathag

Banned
tomo pauk said:
You can note that the required effective range is 150-200 yds vs. what became the M1 carbine. That means the barrel can be half of the lenght of what M1 used - a weight saving. Reduce the use of wood as much as possible, replaced by plastic front stock and the wire buttstock - again reduces the weight. Receiver can be lighter, since a less powerful cartridge is sufficient (even the 7.62 Tokarev works here).
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I would go with a very slim steel rifled barrel, but supported by a magnesium alloy sleeve that does double duty toast as trunnion/ fit into stamped steel lower.
 
marathag

marathag

Banned
Orcbuster said:
Its at this point that its realized that the requirement is stupid and unneccesary and its changed
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There might be good reason for the light weight.
If no company could meet the requirements, they would get changed slightly, like for the Jeep

But even difficult targets, like for the USAAC 'Hemisphere Defense' contract had Boeing, Consolidated-Vultee, Douglas and Lockheed have designs, with the last two dropping out before metal was cut.

But for this TL, consider it set in stone.
So how do you get there with a 1300J cartridge with need for 200 yard accuracy?
 

cortz#9

tomo pauk said:
Steel stampings here, aluminium alloy there, bakelite pistol grip and hand grip? Barrel length can be about 10 inch, as on the SMGs of the day, again less weight than the long barrel used on the M1 Carbine.
I'd certainly prefer layout of an Uzi, or a (stocked) pistol to keep the weight down - in other words, magazine goes in the pistol grip, behind the trigger.
The wire buttstock like used on the Grease Gun should improve the hit probabilities beyond 100 yds, while not being too heavy.

@cortz#9 - can you whip up something here :)
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Let me give it some thought, will get back to you.
 

cortz#9

Sten-Mk7.png


Sten Mk. V converted into an Uzi type SMG.

Bullpup Car..png

Bullpup M1 Carbine inspired by kits for combining Ruger mini-14 into a bullpup.
Should've used a wood stock M1 Car, will post one later.
 

Cryhavoc101

I am going to be honest here (Note: I am a big fan of the M1 Carbine so do consider that bias regarding my answer) making some weapons too light as IMO the OP has asked for ends up making the system much less good

We can as has been shown make the M1 Carbine lighter but IMO this often makes it worse as a weapon system.

The folding wire stock was not as good as the wooden one etc but it is a possibility - some folding stocks are very good such as the Sterling SMG / E-11 blaster rifle for example

However as has been said making use of alternative materials such as Bakelite, instead of wood could make the weapon lighter - probably not 1.5 pounds lighter but still

Issue is can the leveraged industry that made the OTL M1 carbines produce such a lighter weapon

I know that later war (1942 plus) BARs built by the likes of IBM switched to Bakelite/Resinox 'plastic' for the stocks and grips (made by a company called Firestone who primarily made tires) although this was driven by a shortage of walnut as much as it was attempting to make the weapon lighter and more modern etc

But the tech was there.

So Assuming that the lighter stock and grips can be produced in sufficient numbers without impacting other needs then it should reduce the weapon weapon weight - but probably not as much as 1.5 pounds

At the end of the day its still already a very light weapon - for the same weight as a loaded M1 Garand 'with sling' you could have an M1 carbine with magazine and sling and 150 rounds of ammo in 15 round clips
 

tomo pauk

CB13 said:
Or something like this: Mini Uzi Carbine.... although with smaller hands (smaller people) in 1940, it would probably need a short case like .357 Sig or 7.63 Mauser to be effective to 150 yards.
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Hmm - shape and size of Mini Uzi, 8-10 in barrel, with Browning action inside?
 
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