Minimum chamber walls thickness to safely handle .22lr round?

zZ_denis

zZ_denis

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Im working on a custom .22lr project, and was wondering if anyone knew exactly how much steel i would need around the .22lr case to make sure it doesnt burst? I know that it will depend on the quality of steel, but lets say i used averege, typical, non stainless gun barrel steel.
Thanks!
 
.22 rim fire barrel liners are only 5/16" in diameter... I am sure you would want a barrel larger than that just for looks...
 
zZ_denis said:
Im working on a custom .22lr project, and was wondering if anyone knew exactly how much steel i would need around the .22lr case to make sure it doesnt burst? I know that it will depend on the quality of steel, but lets say i used averege, typical, non stainless gun barrel steel.
Thanks!
Click to expand...

Hi

The minimum with steel that you absolutely positively know for certain is good is pretty small. If you want to keep pressure down, chamber the rifle for 22 shorts. That will keep somebody from putting a high velocity round in there.

Normal receivers are in the 3/4" to 1" diameter range. That would put a typical wall thickness at a bit over 1/4". I suspect you can go down below 1/8" with a 22 short.

Bob
 
A few years ago, I made up a firing mechanism for a test and turned a piece of .22 barrel down to .310" over the front half of the chamber. I fired 2 long rifle shells out of it without it bursting. That is a wall thickness of .043". If my memory is correct, I had been going down in steps of .020 off the diameter and firing 2 long rifles shells each time. I am not suggesting that you make a barrel that thin, only that there is a considerable margin of safety in terms of barrel thickness, with most .22. You might want to measure the barrel diameter on some of those survival guns if you can find one. Amongst other things you probably want a barrel at least .375" diameter just to be strong enough that you don't accidentally bend it.

cheers mooncoon
 
Dig out the pressure specs for the cartridge. SAAMI "should" have the .22 listed.

Work out the surface area of the case.

Find out the tensile strength of a typical, good quality, mild steel.

Work out what the cross section required would be to reasonably expect it to not blow up, and what you would want as a margin for safety.

Well, if you really want to know.... :)

The whole process is worked out in a book available from Village Press, in the US, called IIRC, Building a Single Shot Falling Block Rifle, by Mueller or Muller. About $17, and it covers all the math stuff for calculating strengths for the barrel and breech block supports for a .225 winchester rifle (the caliber he built, thus the example used).

Street hoods from way back were making illegal personal weapons out of car and radio antenna tubes going way back. Most of them didn't blow up, if what gets read, is to be believed.

Minimum sized barrel, is gonna be really whippy and flexible!

Cheers
Trev
 
It depends on the specific steel used. Having said that, there are a lot of handguns with some thin barrels. Consider how thick the wall on a revolver cylinder is on some .22 guns.
 
Rudy H said:
It depends on the specific steel used. Having said that, there are a lot of handguns with some thin barrels. Consider how thick the wall on a revolver cylinder is on some .22 guns.
Click to expand...

Hi

.050" thick wall tube is about what you see on a lot of bicycles. It's fairly easy to dent. It's lighter than any barrel I have ever seen. Also pressure in the barrel is lower than pressure in the chamber. Pressure drops pretty fast once the bullet gets moving.

Bob
 
Thanks a lot for all the replies, guys.

I have one more question. Would it be safer to fire CCI stingers in a rifle with very thin chamber walls? Its a hyper-velocity round but the case is made of steel (i think) instead of brass, which probably makes it stronger.

Thanks again!
 
i think you are overstating the concern re; chamber pressure of .22 LR....the barrel liners used on many custom 10/22 barrels are quite thin and can handle the pressure of Stingers or we'd have heard about it. Stingers are prob. not made of steel as much as nickle plated brass. I just hope that by all this that someone isn't going to play around with making a barrel/chamber out of something not meant for that purpose, and lose an eye or something.
 
Hi

I'm still not sure what the ultimate project is here.

One other thing to consider - if you get the barrel and chamber to thin, you can deform them accidentally. I suspect that a barrel that is egg shaped isn't going to work very well ...

Bob
 
Be aware,

A barrel liner is designed to be supported by a barrel that it's lining....

I don't know how safe it would be to use the barrel liner as the barrel alone.

NS
 
trollpatrolwatching.jpg
 
The revolver chamber theory doesnt really apply, because the inner 70% of the cylinder is solid steel, the outer 30% is the thin part, and that is special heat treated steel, and a liner isnt exposed to the outward force of the cartridge like the chamber is...and is reinforced by the barrel. This whole thread is scary....go to the home depot and look how thick they make those 22cal cement nailers (and they shoot blanks) and ask yourself if you really want to risk loosing a finger or an eye. Err on the side of safety.
 
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