Recently reloaded some 40 cal in 180gr SWC with 5.2 gr or WW231 which is well in the safe zone. OAL case length was to fit the chamber of the Glock 35 I was loading for. The plunk test showed I was spot on length wise. Shooting them revealed these was pressure excess pressure in my opinion based on what father taught me 55+ years ago. A flattened primer means its hot but when the primer starts coming back on the firing pin look out. That my first experience with the excess pressure of this type.
People were shooting 9mm's and I examined their factory loaded brass and found the same thing. So what gives? Was Papa wrong? Everything I have been taught was an error?