I think by the time they put a shell in a gun at the proof houses, they are pretty sure the gun is going to be fine. Someone posted the process here long ago. It involved detailed inspection for defects and dimensional inspections.
That's what I thought Chuck, but it seems every time there is a discussion here about minimum safe barrel wall thickness, one or two guys chime in about a gun that has passed Nitro re-proof with very thin barrels. It kind of makes me wonder if the proof houses don't have at least one employee whose attitude is, "If you're stupid enough to send this POS in, I'm crazy enough to blow it up." I don't recall exact dimensions, but I do recall remarking on one that was out past the forearm that was only a few thou thicker than a matchbook cover, which is about .016".
Of course, I have also often wondered how how anyone knows if the obvious honing on a given barrel was done before or after the proof marks were put on.
