I was trying out a load of 60.2 grains of Reloder 26 with a 150 grain Sierra Gameking in the 270 Winchester. The first, and only, shot fired registered 2975 fps on my chronograph but also blew the primer. There were no other signs of excess pressure except for the primer - even the velocity seems reasonable. As for the primer itself, it was still in place but I had leakage along the edge of it in one place. Is there anything that can cause this other than excess pressure?
