The 1 slamfires I've read about with AR-15s are a results of a caught firing pin extruding from the bolt facial place developing it to work like an open bolt submachine. It will likely hearth from battery like that. GM primers is all I use whenever they can be obtained. https://beaujwjue.blogocial.com/top-large-pistol-primers-1000-count-secrets-67395378