The 22LR firing pin, specifically, in either the dedicated 22LR upper or the conversion?
Just curious since I recently had it happen to mine for the second time. The first breakage was right around 4,000 rounds. No biggie, the firing pin is $15 on their website. Replaced it and continued until the replacement broke, once again after right around 4,000 rounds. Ordered another one and replaced. I emailed CMMG about it after the first breakage but never heard back from them. Both times the firing pin broke right in the middle where it's got the cutout for the retaining pin.
They have upgraded their bolt since then though, it now has a cotter pin retaining the firing pin rather than a retaining pin that you had to use a punch on. I really like their uppers except for the firing pin thing. The first upper I got had a parkerized bolt with a receiver plate that broke after about 4,000 rounds; the 2nd bolt I got (stainless) has been almost flawless with probably only 4 or 5 malfunctions in 8,000 rounds ... except for breaking it's firing pin twice.
I do accidentally dry fire it sometimes at the range since I don't bother counting how many rounds I've fired and often stop at the click. Could just be user error. Just wondered if this has been happening to anyone else.
Oh yeah, my other complaint with the company is their shipping policy. You can order a $1 extractor spring on their website that could easily fit in an envelope and they'll charge you $10 for shipping
