At 2,000 rounds I disassembled the bolt on my dedicated 22lr upper to find that the firing pin had broken and the rebound spring is a couple of pieces. CMMG customer service (Brian) sent out two replacements of each without any delays, question or charge.
I've since fired another thousand trouble free rounds.
Tonight after yet another session with reliable function and commendable accuracy, I checked the bolt for confirmation that all was as it should be. I found the firing pin spring shattered into no fewer than eight pieces. The two non-standard aspects of my installation are a Lakeside heavy recoil spring and a Larue two stage trigger.
1. Are any of you experiencing frequently broken rebound springs?
2. Are any of you successfully omitting the FP spring and still getting reliable function?
I am not at all sure that this is a problem of CMMG's making; I could imagine that the heavy recoil spring is increasing bolt velocity that could be harder on a rebound spring. I suppose I could just order these springs by the dozen, but I would prefer to know what the problem is or whether this spring is needed.