Customer brought in an AR built by someone else on a C3 Defense receiver set......possibly by C3 themselves, but worked on at least once since then.
The bolt catch didn't function properly. It felt like there was no spring or plunger under the catch.
The receiver extension was of the type with the wide, fixed loop sticking out the sides, which prevented me from getting to the bolt catch pin, so I removed the buffer system and it's parts from the rear of the receiver.
When I did, I found this:
Instead of a detent spring and detent. there was half a detent spring and two detents. That's a novel approach.
When I removed the bolt catch, this is what I found:
The aluminum was severely peened over the head of the bolt catch plunger, trapping it compressed below the surface. I told the customer that he would have to leave it with me in order for me to fix. He asked what my recommendation was, and I said that I'd trash the billet C3 lower and replace it with something forged and closer to milspec. Additionally, for what I would charge to free trapped plunger, I could sell him a forged Aero Precision lower instead.
Pulled all the parts off the offending lower and rebuilt them into the new Aero lower. Replaced the half a detent spring with a complete one. Replaced the receiver end plate with one from Forward Controls Design that has a QD sling swivel socket. Trigger appeared to be an ALG Defense ACT, which is an damn good one.
Customer hit me up the next day and said she runs like a champ.
The bolt catch didn't function properly. It felt like there was no spring or plunger under the catch.
The receiver extension was of the type with the wide, fixed loop sticking out the sides, which prevented me from getting to the bolt catch pin, so I removed the buffer system and it's parts from the rear of the receiver.
When I did, I found this:
Instead of a detent spring and detent. there was half a detent spring and two detents. That's a novel approach.
When I removed the bolt catch, this is what I found:
The aluminum was severely peened over the head of the bolt catch plunger, trapping it compressed below the surface. I told the customer that he would have to leave it with me in order for me to fix. He asked what my recommendation was, and I said that I'd trash the billet C3 lower and replace it with something forged and closer to milspec. Additionally, for what I would charge to free trapped plunger, I could sell him a forged Aero Precision lower instead.
Pulled all the parts off the offending lower and rebuilt them into the new Aero lower. Replaced the half a detent spring with a complete one. Replaced the receiver end plate with one from Forward Controls Design that has a QD sling swivel socket. Trigger appeared to be an ALG Defense ACT, which is an damn good one.
Customer hit me up the next day and said she runs like a champ.
