I'm not good with ar rifle nomenclature so please bare with me on this. Bought a new Ruger AR556. Was reading where Rugers new carriage has a cut out under the firing pin which may or may not cause a bent firing pin. So I bought a new carriage bolt assembly from Bravo Co. Went shooting for first time. Shot around 50 rounds with original bolt assy. no problems. Switched to BCM bolt assy. and shot around 150 rounds. no problems. I do not have a head space tool and totally forgot about that being done. When cleaning rifle I noticed the part of the barrel where the front of the bolt lugs touch barrel , the barrel has scratches on it that I really did not noticed when cleaning rifle before shooting. Is this a problem or is this normal? All responces are appreciated. Thanks.