Back when the fire was a different place, we used to have a gunsmith that posted here a bit. Was in the magazines, made very accurate rifles.
He also had pressure testing equipment to go along with a 100 yard range (underground IIRC - made from shipping containers). With that equipment he did a bit of an experiment with a 300 WM. Over loaded it till it let go.
Eventually he blew the last 5-7 inches of the barrel off. Way over max and verified with test equipment.
Not a single "generally accepted" sign of over pressure that most reloaders look for. Brass issues, case failure, extraction issues etc. NONE of those happened before that barrel let loose and the pressure test equipment proved this wasn't a bad barrel but well over max loads PSI/CUP wise.
Moral of the story was that generally accepted signs of over pressure were NOT reliable and it was definitely possible to be well over max without notice.
