@oli700 ,
Rather than the hammer, I'm wondering if it's not the trigger group housing on your CMC unit that's chewing up the carrier. The width of the scarring and greater damage at the outer edges makes me think that could be the culprit. Looking down into the open lower, do you notice any movement in the housing when you manipulate the trigger? If the rear of the housing indexes up high enough when the trigger is pulled that could cause contact. Is there any wear on the top surface of the housing that would suggest contact with the carrier?
Rather than the hammer, I'm wondering if it's not the trigger group housing on your CMC unit that's chewing up the carrier. The width of the scarring and greater damage at the outer edges makes me think that could be the culprit. Looking down into the open lower, do you notice any movement in the housing when you manipulate the trigger? If the rear of the housing indexes up high enough when the trigger is pulled that could cause contact. Is there any wear on the top surface of the housing that would suggest contact with the carrier?