I just put together by 450 bushmaster build. The barrel is from bison gun works. Long action with 06 bolt head. Set headspace with ptg gauges. Now to the question. Something is eating up the rim on the cases. Doesn't mar them every cycle but about every other one. Have not shot gun yet just cycling factory hornady ammo through it. You can feel it hang up sometimes on something and bolt has a hard spot on it when closeing. When it's ejected you can see mar spot on rim.


What's going on???