Are you getting the velocities you want before getting the overpressure signs? I'm starting to think even the factory loads show overpressure in my gun.
I wanted to try Barnes new 150 gr. TSX BT bullets a while ago, but there was no loading info. I tried what was the minimum load of 83 grains of RL-25 with the Hornady 154 SST I had been shooting at 3100. With the TSX, the first load blew the primer and extruded brass into the ejector slot jamming the bolt opening rotation. I worked it up and down a few times, and it ejected the round and primer fell on floor. The chrono showed 3358 fps., the primer pocket was expanded to .222 from .208. No more solids for me, until there's some solid info in this cartridge. Savage has stopped chambering any rifles for the RUMS...but only tell me they were not selling well. I'm getting good accuracy with the SST's an inch at 100 yds. is easy at 3100 fps.
primers when FL sizing with RCBS-X dies:
Fed 215 on left handload, Rem factory round on right,
notice Fed has more flattening, Rem has a crater and less flattening????? So far neck sized cases show very little flattening.
One case that started to separate on third firing note strange dent at shoulder, gases going forward?????