doublegunshop.com - home Forums General Discussion DoubleGun BBS @ doublegunshop.com Barrel wall thickness

I am a non-expert when it comes to safe barrels, so can anyone give me the straight facts on how thin a barrel can be and be safe. I only use low pressure shells in my old guns, but if a gun has fairly open chokes and 8" from muzzel the thinnest measure is 21 thou. in one barrel, 25 thou. in the other, is it safe to shoot a lot of low pressur shells such as RST's.
This is a light gun and I have an article from British guntrade saying the minnimum should be 19 thou. What say the rest or you??? Thanks, Larry

Thin barrels are very easy to dent. I have seen barrels pass proof at less than .020. I use to shoot a gun with barrels as thin or thinner than you are talking about. It is not as much how thin as where they are thin. A foot past your front hand is fine if between the chambers and your hand then that is another matter to me. Pressure drops slightly the further down the barrel you go from what I have been told. Highest within an inch of the chamber and much less near the choke area. Low pressure loads of the correct length should be fine.

teloc: KY John is correct, but personally I would not gamble my hand with a barrel that measures 21 thousandths anywhere along the tube. JMHO

Best Regards, George

Pressure is highest within 1 to 1-1/2" from the standing breech, not from the front of the chamber. That's probably why the thickest walls are over the chambers. Ya think?

I shoot a century old 16ga German sidelock which has an area of .020" thickness about 6 inches short of the muzzle. RST 7/8oz 2 1/2" shells are pretty steady diet for it. If it were that thin within first half of the barrel I would not. But there are more factors to consider. Look at a pressure curve for typical shotgun shells and you will see that the pressures really drop off dramatically once a few inches beyond the chamber area. Some of the newer powders giving high velocity loads in latest shells extend that high pressure area further done the bore to attain those velocities. So they are definitely not for older thinner barrels.

As stated, wall thickness does not determine proof. This is from 1891.


Pete

My Arrizabalaga barrels at the thinnest are about 25 thou; London bests run about this or slightly thicker. 20 or 21 would make me nervous.

A good friend and I were examining a Brit gun he was considering buying. There were some exterior pits within maybe 4" of the muzzle, and he decided to pass. Afterwards, as we were hashing over pros and cons, something occurred to us: How significant could those pits have been in that location, since people shoot guns all the time that have actual HOLES in the barrels in the same area (ported)? Answer: not very significant.

Does anyone know what the chamber pressures are for 12 gauge Winchester "Low Noise Low Recoil" target shells? I thought I had seen a post on this site a couple of years ago saying it was 5950.

Atticus

A few years ago .020 was considered the minimum. That was changed to .025 not too long ago.
I believe Greener as a trial, proofed a .008 barrel. Not recommended at home.