I spent a bit of time googling for spare parts for the Atchisson-Ciener/CMMG .22lr conversion. In addition to finding someone that offers spare recoil & firing pin springs (here), I found a few interesting links for troubleshooting the unit.
I had a little bit of free time, and I love to tinker, so I decided to strip it down and give it a good cleaning and see what the innards look like. There's a thread on TOS that shows how to field strip the conversion unit for cleaning.
After reading this thread I decided to venture into the firing pin and clean up that area. After driving out the FP retaining pin, I had to work pretty hard to get the FP out. I figured maybe it was pretty gunky, but after cleaning up the channel with a q-tip and wiping down the FP I inserted it to see if it traveled freely. Oddly enough it did not; there was a lot of binding.
I grabbed a small strip of 600 grit paper and soaked it with oil, wrapped it around the FP and gently turned it. Every few turns I would insert it into the bolt to see if it dropped free. After a few minutes I massaged the FP so that it rides freely in the bolt.
I wonder if the FP not moving freely in the bolt may have caused some of the failure-to-fire issues that crept up with different brands of ammo. I'm going to run the various ammo again at my next range visit to see if any changes are noted. Additionally, I may try clipping one coil from the FP spring to see if that further alleviates light primer strikes.
I found one small burr on my extractor and I plan to remove it from the bolt and then clean up any rough spots - maybe that'll reduce extraction issues that creep up... I'll post further updates as I continue to get this thing tuned.
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