So, trawling around the internet, I found a mention of a Chapuis MR73 revolver with proof load paperwork at something around 3900 bar, or about 56,500 psi. That’s a touch over 60% in excess of maximum pressure for .357mag. Standard proof loads for .357 are typically more like 45,000psi. I was wondering if the Mulhouse Manurhins also have proof pressure at this amount. It might be a data point in favor of the Chapuis guns being similar enough to the Mulhouse guns.
From other random internet chatter, it seems that the Mulhouse guns had an alloy from these folks:
https://www.aubertduval.com/about-aubert-duval/
I have no idea if Chapuis allegedly not using whatever special alloy that was previously used means much if the proof pressure is the same, since at the end of the day, if it demonstrates similar mechanical properties, it doesn’t particularly matter if it’s exactly the same or not . Especially since as far as I know, no one who knows specifically what metals, forging processes, or other treatments were or are in used in either make of gun is talking about testable specifics here.
If anyone reading has any insight on this, or just a proof pressure certificate for a Mulhouse gun, I am all ears.