I can't find it so
 

I read not long ago safe barrel wall thickness but my computer don't remember so well so what is min. wall thickness.

Calvin, people have generally said here .025 for a 12ga , but the British proofing houses will pass down to .020.

I am personally uneasy with anything close to .025 in a 12. Many light small bores came from the factory at close to .025, so that is a bit different. Most Parker 12's were factory produced at least .035. I would have to look up the hoop stress formulae again, but the greater the diameter, the greater the wall thickness needs to be to withstand the same internal pressure.

I know you are a 10ga guy and I don't have enough experience with the 10's to know the average factory wall thickness on them or what would be acceptable after honing. I know lots of 10 ga guys shoot some heavy loads. If your intent is to load 1 1/4 3dre, then that is such a light 10 load, it wouldn't make much difference. If you want to experiment and see how much you can get, you need to know more than I can tell you.

I don't believe that is a totally accurate statement Bruce---and may be a bit misleading. In direct correspondance with Michael Lynch, the chief inpector at The Birmingham Proof House. He told me that they (the BPH) will inform their customers if the MWT falls below .020 even though it may have passed proof below that number.

Thanks for the clarification. I'm uneasy with any thin walls regardless of passing proof. Don't they proof it and pass it for rather light loads?

British proof is not all it is cracked up to be and it is getting worse. According to the other shotgun forum, they are blowing up guns at a pretty great rate. Even the Brits are getting suspicious.

I don't know how you can get it done now but used to you could get them standard proofed or proofed for service. Proofed for service was a good way to go, you told them the load you wanted to use in the gun and they proofed them as just slightly above that charge. I think now they use proof pressures that have been set up by the European Union and some of them are pretty sporty.

Destry

My 12 measures .33 at 18 inches and .29 at 22 inches. ch