Looks like the radius f the primer cup took a hit to flame cutting. Thats the part of the primer that is work hardened from being formed into a cup so it could be a tad harder than the rest of the primer material. The flat face of it needs to be soft enough not become pierced but strong enough to control a certain amount of pressure.
Size of the flash hole could have something to do with it as well as the brand/lot of the primer and then how the sheet of primer cup material was pressed out to make them. Looks like the flame cutting came from inside the primer cup and not from around it so the skirt apparently did its job.
I bet the bolt face has become pitted. That sucks.
Size of the flash hole could have something to do with it as well as the brand/lot of the primer and then how the sheet of primer cup material was pressed out to make them. Looks like the flame cutting came from inside the primer cup and not from around it so the skirt apparently did its job.
I bet the bolt face has become pitted. That sucks.