markt
10-04-14, 12:46
I have a CMMG 22LR Bravo conversion bolt that was recently sent to me by CMMG as a replacement for some ongoing OOB and extraction issues. Unfortunately, this bolt has its own issues.
I put the bolt in yesterday and proceeded to fire a few rounds. After a few rounds in the mag, I noticed the bolt was getting stuck in the locked back position. Upon closer inspection, it looks like the extractor pin was riding too high in the bolt and getting caught up in my receiver at the rear of the ejection port.
The pin has left a large scratch and gouge in the metal of my BCM receiver, causing a burr to be formed, further causing more friction and unreliable cycling of the bolt.
I took the bolt apart and drove the extractor pin out to investigate. It seems that it had been driven into the bolt too deeply with some force. When I reinserted the pin back in the bolt normally, it now sits lower at the top but too low at the bottom. It now drags on the bottom and causes enough friction on the rail that the bolt won't cycle smoothly at all. This seems to explain why they may have felt the need to drive it in deeply at the factory to ensure it cleared properly at the bottom.
This seems to be a design issue. I see no reason why the extractor pin hole could not be drilled less deeply and the pin cut shorter. This would alleviate the risk that the top of the extractor pin sits too high, scratching and gouging the receiver as has happened in my rifle.
For anyone with a new CMMG 22LR conversion, I highly recommend looking at your extractor retainer pin and also your receiver for contact before using it too much. Inspecting a friend's rifle with an older CMMG 22LR conversion, he too had the scratch but not a deep as mine. It seems that maybe the issue has been around for some time...
For your consideration,
MarkT
28853
28854
28855
I put the bolt in yesterday and proceeded to fire a few rounds. After a few rounds in the mag, I noticed the bolt was getting stuck in the locked back position. Upon closer inspection, it looks like the extractor pin was riding too high in the bolt and getting caught up in my receiver at the rear of the ejection port.
The pin has left a large scratch and gouge in the metal of my BCM receiver, causing a burr to be formed, further causing more friction and unreliable cycling of the bolt.
I took the bolt apart and drove the extractor pin out to investigate. It seems that it had been driven into the bolt too deeply with some force. When I reinserted the pin back in the bolt normally, it now sits lower at the top but too low at the bottom. It now drags on the bottom and causes enough friction on the rail that the bolt won't cycle smoothly at all. This seems to explain why they may have felt the need to drive it in deeply at the factory to ensure it cleared properly at the bottom.
This seems to be a design issue. I see no reason why the extractor pin hole could not be drilled less deeply and the pin cut shorter. This would alleviate the risk that the top of the extractor pin sits too high, scratching and gouging the receiver as has happened in my rifle.
For anyone with a new CMMG 22LR conversion, I highly recommend looking at your extractor retainer pin and also your receiver for contact before using it too much. Inspecting a friend's rifle with an older CMMG 22LR conversion, he too had the scratch but not a deep as mine. It seems that maybe the issue has been around for some time...
For your consideration,
MarkT
28853
28854
28855