I have some cratered and pierced primers in my build. I'm using a TacFire BCG, RRA LPK in a New Frontier lower, barrel is (I think) Anderson 4.5".

Is this a headspace issue? Stock hammer spring too strong?

I looked at the pin tip and it looks ok to me. It's rounded. Not polished, though. I can't figure out how to measure protrusion while fighting the spring though. 

I think I have one of those protrusion gauges from Brownell's but it would likely take me a very long time to find it. And I'm not even sure if a firing pin protrusion gauge for 5.56 would be the same for 9mm. I could take it out and hit it with a buffing wheel and some rouge and see what happens.

I hit it with the buffing wheel and polished the tip of the firing pin. I think it could be an issue with the firing pin not being large enough in diameter to fill the hole in the bolt face. I guess I will just have to send it back to the factory along with some fired cases or something. 

Just as an update, I ordered a KVP bolt and the firing pin hole is visibly smaller. An email request for return authorization from Tacfire has gone unanswered for the better part of a week. I am going to try the place I purchased the bolt from.