This is very interesting. I am building three small ring projects and will make necessary modifications to minimize this threat. I will post my mods as I make them.
Something I did not know at the time I posted in this thread was that ammunition pressures rise as the ammunition gets older.
I had planned on loading light..... these were factory ammo from 1970-something..... I had 139 and 175 grain bullets. The 175's kicked like an angry mule, I had 2 or 3 pierced primers, and the case heads looked like h
Notice that the guy was firing factory ammunition from the 1970's. It had obviously gone bad, increasing pressures, and piercing primers.
Since I have learned about the risks of old gunpowder, I have been collecting a few good examples, as warnings about old cartridges and old gunpowder.
The lifetime of gunpowder is unpredictable, the Air Force calls it indeterminable, which confuses a number of people, including Air Force personnel, as they confuse indeterminable with indefinite. (infinite) Indeterminable means
“not able to be definitely ascertained, calculated, or identified” Basically, the stuff fails when it fails. A reasonable lifetime for double based is 20 years, single based 45 years, but, sometimes unreasonable things happen with gunpowder. I think this gunpowder was less than 10 years old before bottles started auto combusting because the stuff had aged unexpectedly quickly.
Combustion pressures also rise in old cartridges and this is what the OP was experiencing. His action was doing quite well for an old military action. Things could have been worse as the 1892 Mauser action has few gas venting protection features. If the OP had been using new factory ammunition or reloads with fresh gunpowder, assuming proper reloads, then he would not have experienced any of the over pressure conditions posted in this thread. That is the absolute first place to start with one of these old actions. Shoot appropriate ammunition, don’t shoot decades old stuff, and stop shooting old stuff if it shoots signs of overpressure.
Don’t shoot anything that looks like this: