Steel cases

Hello, i’m working on a gun that need special cases made of steel, for the operating.

It’s a very simple design, even though it’s magazine fed, through these rimless cylindrical cases.

My question is, the cases got 1mm wallthickness, contains the ordinary brass round, and will be put into the main chamber of the gun. Will these cases get stuck in the chamber? What steel should they be made of?

I think you need to add a bunch of information before anyone will answer.

Here’s my idea
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It’s a slamfire action, that feeds cylindrical steel cases in the same dimension (diameter) as the barrel, the cases contains the round. When a case is inline the barrel, a spring slamfire the barrel which force the case towards the fixed firing pin, like a ordinary slamfire.

In order to get the spent case out of the gun, the ”breech face” can be pulled up, like those backloading shotgun cannons, and the barrel will force the case out. Then, when the barrel is pulled back, the gun will lock by itself, and at the same time recock the barrel, and a new case gets inline the barrel.

I will use a simple trigger mechanism to catch the barrel.

The idea behind this gun is to keep it simple and very reliable, with no jamming and lose parts that can hassle. Basically a design for homemade guns without any advanced equipment..

I made my version very small too.

I will use hyper velocity 22lr, the cases will be made of 3 or 4mm thick steel, the same thickness as the barrel.

My original idea was a bit different, but it got to complicated.

I got one concern about this design, and that is the space between the face of the case and the back of the barrel. Will gasses leak through this space? The spring will force them together, so it should not be any space between them, but in practice i belive it could.

seems kind of overcomplicated, just make a normal hammer fired blowback like everyone else
or a slam-bang pipe shotgun if you're really on the cutting edge of cheap garbage

but to answer your question, 1mm wall thickness is plenty to contain .22lr and you will get some gas leakage since the steel sleeve is not obturating to fit the chamber so make sure to machine it to a very close slip fit (which negates any notions of it being reliable, cheap to fire or easy to assemble)

for a roundabout way to an acceptable idea of clearance, figure out the area of the cylinder gap on a revolver of the same cartridge. Figure that area for the maximum clearance between chamber and chamber insert.

This is basically a slamfire shotgun, but instead of shotgun shells i use 22lr, and instead of slamming by hand i use a spring.

For this gun, you will need two barrels/pipes that you slam inside the ”receiver”/chamber. One is used as the ordinary barrel, one is cutted down and used as cases, and loaded with rounds.

The magazine is very simple, it doesn’t got any lips, it’s just a rectangular tube with a spring in the bottom. There’s no bolt that need to feed the cartridge, the whole case is perfectly inline the barrel, to be slammed down at the fixed firing pin.

The barrel won’t be totally supported inside the ”chamber”/female pipe, because of the magazine hole, so it has to handle the pressure by it’s own, since the barrel can’t be thicker than the cases, the cases will be at the same strength as the barrel, since i aim to make them of the same material, so the chamber won’t be necessary to support them from blowing up, like a ordinary brass round, in this case it just makes the mechanism of the gun work..

I would like to know more about the pressure curve, i know that the pressure inside the chamber where the round is located is much higher than at the muzzle, in this case the magazine hole is about 0.8 inch infront of the round, and it’s at this location the barrel won’t be supported.

Without the magazine hole, the barrel and cases could be made thinner, since they could be fully supported inside of the female pipe/main chamber.

But even if the barrel and cases can handle the pressure by themself, will play/space inside of the ”chamber” be a problem? For a ordinary pipe shotgun, would space be a problem?

Maybe i’m wrong, but i belive this design is very simplier than any blowback gun, and you could basically build this gun from the material you can get from a hardware store.

Firing from an "open bolt" (or in your case an open barrel)? I'm sure the ATF would like to talk to you. The fixed firing pin / open bolt is just the thing for a simple machine gun and that is why you do not see any of this type of action in semi auto on the market anymore - to easy to convert to full auto.

You might want to check the laws on making a zip gun.

Federal law allows you to build/make a firearm as long as it adheres to the NFA 1934 requirements. Local laws may prohibit it though. The ATF considers open bolt guns to be machine guns.

Just one man's opinion, but it sounds like either a prescription for legal troubles or one of the regulars is having some fun with us under an alias.

In either case I think it would be folly to offer gunsmithing advice to this poster. He's already been informed as to the possible legal hazards of making an open bolt repeater.

I was think and introduction to Rube Goldberg might be in order

This gun has to be recocked and case-released, it’s a repeater, no way could this gun be converted to full auto. So i don’t see any legal issues with this at all, as long as i use a rifled barrel.

Because of the simplicity of the design, and that it allows easy and fast fire rate comparing to a single shot, or a ordinary slamfire pipegun, i believe this design could be the easiest gun to build that allows a good rate of fire.

All other designs is much more complex, a pepperbox that is manually indexed is closests for its simplicity, but much more complex than this, the makeing of the cylinder needs expensive equipment.

The only thing that bother me with this design, the only thing that could go wrong i think, as already mensioned, is the space between the rear of the barrel and front of the case.

Unlike a revolver, the space isn’t fixed, the spring force the barrel and case together, which could make them very tight but maybe also make them bounce when hitting the firing pin, depending on the spring to i guess.

Another difference, is that the barrel and case is inside a chamber/female pipe, so the hot gasses is captured, it would be easy to drill some vent-holes, but will it be necessary?

Give me your thoughts on this.

I would suggest you call your local ATF office and run the design past them before getting too much effort in to it. Even though you say "it can't be converted to full auto" the law doesn't really care. Just being able to fire from an open bolt puts it in the realm of "machine gun" as per the law. It'd be best to get a letter from your ATF office stating that the design is okay.

JMHO

-Ron

MetalCarnage said:

I would suggest you call your local ATF office and run the design past them before getting too much effort in to it. Even though you say "it can't be converted to full auto" the law doesn't really care. Just being able to fire from an open bolt puts it in the realm of "machine gun" as per the law. It'd be best to get a letter from your ATF office stating that the design is okay.

JMHO

-Ron

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The BATF decided long ago open bolt firearms are a NOGO and forced companies to change their designs to closed bolt to stay in business.

Maybe your design is legal and simple but the steel sleeves or chambers would quickly become an issue. You go to the range with ten but return with five because three fell in the tall grass and one dropped into a puddle and can't be found and one got stepped on. The hardware or sporting goods store does not stock the Monday Special steel inserts so you buy a piece of round stock and spend the next few hours making a couple of dozen of them, time you could have spenting shooting with a more complex but reliable revolver.
There were semi auto pistols made (and maybe some rifles) that used the blow forward principle. The slide was stationary and the barrel moved forward when fired and a spring drove it back over the next round in the magazine. That was about 100 years ago and was short lived. The inventive process is frequently a number of dead end paths.

Gazz said:

The ATF considers open bolt guns to be machine guns.

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open bolt is fine so long as there is no magazine
ljutic "space gun" shotgun is open bolt, same with the cobray terminator POS and there are a few open bolt .22 single shots as well.

If it isn't a shotgun it also must have a rifled barrel to be legal. That eliminates a lot of garage shop designs. If it is a shotgun it must have a barrel of at least 18" and an overall length of at least 26".

[486] said:

open bolt is fine so long as there is no magazine
ljutic "space gun" shotgun is open bolt, same with the cobray terminator POS and there are a few open bolt .22 single shots as well.

Click to expand...

But is sounds as if he is planning some kind of magazine to hold the steel cylinders which contain the .22 cartridges. If I understand his posts correctly the cylinders act as ejectable, reusable chambers that can be fed, fired, and replaced with loaded ones by manipulation of a mechanism.

It sounds like he's trying to make something along the lines of the homemade slamfire shotguns used in the Philippines during WWII, except with a magazine for rapid fire.