range report and question

I'm not sure if this belongs here, but I think and hope so. At the range today, I was firing a Ruger LC9 and had a few failure to fires. I was using Sellier&Bellot ammo. After inspecting the rounds, I found weak primer strikes and on at least one that had previously fired, I noticed a shaved area around the primer strike crater. This showed up easily due to the red primer sealant they use.
After cleaning and inspecting the gun, I found a small amount of brass shavings in the firing pin channel, which I am sure caused the problem. My question is ...what caused this? Was it hopefully a protruding primer? or worse, a problem with the LC9 and it's bolt face? Maybe lapping the bottom of the bolt face is needed?
I know that it's cheap range ammo, but I have never had this problem with it before. I checked a few boxes of remaining rounds and found no protruding primers.The gun is new with only 50 or so rounds through it so far.
Has anyone had this problem with that ammo and/ or gun? Has it happened with ANY ammo?
I was hoping to carry this one EDC, but NOT until this is remedied.
Until it's resolved, its back to the Glock 36 until summer, at least.
Thanks for any help

You may have sharp edges on the firing pin hole (particularly on the top side) which shave brass as the case slides across it. If so, you can chamfer the opening "slightly" to reduce the sharpness. The shaving can build up in the firing pin chamber until you get light or no strikes. Also look for rough/sharp edges on the firing pin tip. Some fine emery cloth can clean that up. All in all, make sure the firing pin chamber is spotless too.

Thanks, OldVet, that makes sense. I'll definately check that out. From what you said and the evidence, I would suspect the chamfering solution, based on the piece of brass I found. It was elongated and looked like it was literally "shaved" off.