Hi folks.
Can anyone tell me what steel was used by Cooey in their 22lr barrels? I have a barrel (which appears to be interal with the receiver) and I want to use it for a centre-fire rifle. It is long so it would suite a large case, medium pressure cartridge (like a 22/303 Imp).

I think that you will find that the 22lr barrel has a tighter bore than the 22 centerfire cartridges.
Butch

quote:

Originally posted by butchlambert:
I think that you will find that the 22lr barrel has a tighter bore than the 22 centerfire cartridges.
Butch

True.

Don

quote:

22lr barrel has a tighter bore than the 22 centerfire

That's a given. But not a problem. My hornet is a 223 bore and I only use 224 bullets. Maybe that's why I can shoot 60gr bullets in it. It makes no difference to pressure. In any case, I would be hand loading. But for a comparison, consider the UK made two-groove 303 barrel. It has a bore of .304 (mine does) and two narrow grooves. So, effectively, a .312 bullets is being driven down a .304 bore! Someone did experiments with oversize bullets and found that if the bullet will chamber, an 8mm bullet can be fired from a 5-groove 303 barrel without any noticeable rise in pressure.

So, the question still remains, what steel is it? Oh ... it's a i-in-15 twist. (My Toz 22lr has a 1-in-14 twist! But that barrel, although it is 4140 steel, is too short for the 303 case).

(If I cannot determine the steel or it turns out to be too soft, I will build a switchable chambered 22Mag/cast bullet hornet rifle on it).

I have found out that this barrel is a Model 75 military trainer COOEY PATTERN .22 In. But no info on what steel was used - only that it was a single shot target rifle.

Typically rimfire barrels are made of low carbon free machining steels not normally considered suitable for a high pressure center fire. I would guess that the steel is about like the steel used for a muzzle loader.

That was my first thought too. Then I had the 'bright' idea of nitriding the bore. So I took out the barrel to have another look and found that it did not seem like the low-carbon steel one would have expected. It looks and sounds like high tensile steel. I am not sure one way or the other. There are ways of testing it. I could measure the load deflection and even the hardness. It was made to military specs, but .... ?

knowing Cooey, it is probably just hot rolled mild steel.

Thanks, buckbrush. I do notice that the chamber is not cut concentric to the bore. I will set it up in the lathe and turn off the bits I don't want - then I can tell what grade of steel it might be. I'll just use it for a replacement hornet barrel.

Integral with the receiver ? Are you sure it's not just barrel and receiver press fit together ?

Yes, you are right, mete. It looked like an integral receiver at first but why would they do that? The extractor cut-out on the breach face would not be possible otherwise.
But why would they have used a 1-in-15 twist? The model 82 is 1-in-16. (Unless I measured wrong! - Will check again).