Today at the Bench.....

[JeffreyDeGraff]

We have a Mk X varminter in 22-250 . It doesn't take upper end loads to run up over pressure in the heat . I bought a 50 pack of the Winchester 45 gr 4000 fps rat exploders and the 9th round with 90 seconds to 2 minutes between shots dropped the primer out . Upon closer inspection 6,7,8 had gas leaks . Hand loads that repeated the events were 3031 and a 55 gr FMJ at about 3600 fps , a down in the middle load way off max load .

I think it has to do with how the Mauser and specifically the 308 length and sub 30 cal heavy barrels shed heat around the chamber . I don't have any test data to back that but the 7&8×57 wouldn't have remained combat rifles from 1895-1957 if it were a common problem there .
I ran a bunch of loads in a short period of time through a Santa Barbara 98 in 358 Win with no issues but the heat of the day was only about 80 degrees . That action was machined OM for a 4" OAL as an action only sale , not in the standard 3.5" Mauser .

It's interesting that you got spray . By WWII the 98 had a gas escape on the front ring and by design most of the gas and debris ended up in the mag well . The bolt shroud , even the slicked up Winchester ish and others , should have deflected whatever made it down the race ways . Unless like me you shoot left handed .......

I don’t think it’s a problem exclusive to Mausers. Ive had similar problems in remingtons Ruger and Winchesters. As the barrel heats up the round in the chamber gets warmer and can raise pressures. The problem gets even worse when a round is left in a warm chamber for any amount of time, before being fired.


JTD

[Harter]

I don’t think it’s a problem exclusive to Mausers. Ive had similar problems in remingtons Ruger and Winchesters. As the barrel heats up the round in the chamber gets warmer and can raise pressures. The problem gets even worse when a round is left in a warm chamber for any amount of time, before being fired.


JTD

I didn't mean to imply it was a Mauser exclusive thing , but that I had seen it more in the 300 Savage/308 case lengths in the Mauser actions . Similar strings in 308 , 7×57 , 257 Roberts , and 06' in Savage 110 , Rem 700 , and Win M70 don't seem to do it to such a degree that I've lost primers . That thing in the Carcano was all on me .

[JeffreyDeGraff]

I didn't mean to imply it was a Mauser exclusive thing , but that I had seen it more in the 300 Savage/308 case lengths in the Mauser actions . Similar strings in 308 , 7×57 , 257 Roberts , and 06' in Savage 110 , Rem 700 , and Win M70 don't seem to do it to such a degree that I've lost primers . That thing in the Carcano was all on me .

Ah ok. Sorry I misunderstood what you were saying.

Ive never lost a primer that way, but I have had some heavy bolt lifts and really flattened primers on loads that were not normally that way. I find it happens more on really fast cartridges, ie 220swift 22-250 etc.


JTD