greyling22
Member
so I built a 9mm upper around an 8" cmmg guard/banshee barrel and bolt combo. I put a suppressor on it and happily ran it for a few hundred rounds on a standard ar lower (SBR'd) with a stock carbine buffer and spring using the mean arms endomag pmag insert. [the endomag has been flawless from day 1. I cannot recommendit enough. There have been some issues with people running the AR9 version where the built in plastic ejector messes up, but with the cmmg built in ejector it has not been an issue]
But then, between 1 mag and the next, the gun stopped running. IT just would not eject a spent case. I thought, maybe my powder drop messed up and my subsonic loads are not too light. So I chrono'd them, and they were at the same velocity as the previous loads. Out came factory 115grn ball ammo. Still would not eject. So I went home, cleaned everything, still had issues. Of course now it was the weekend, so out came google. Apparently, this is a somewhat known issue where the cmmg system kills the ejector spring. this guy http://c3junkie.com/?page_id=954 has a long writeup about how he has struggled with it. He also has a thread going on about it on ar15.com, and many other guys have chimed in with silmilar issues.
I finally got to call cmmg, they confirmed that yes, I likely had a dead ejector spring and they shipped me 2 for free. They took about 2 weeks to come in and they are about .11 inch longer than the spring I pulled out of the bolt. New spring works great. 40 rounds no issues. Hopefully this new spring doesn't have any issues, but for now, my recommendation has fone from glowing to guarded (ha!) If you have a guard/banshee, I recommend you go ahead and call cmmg and get a couple springs send your way so you have them on hand if/when your's dies.
But then, between 1 mag and the next, the gun stopped running. IT just would not eject a spent case. I thought, maybe my powder drop messed up and my subsonic loads are not too light. So I chrono'd them, and they were at the same velocity as the previous loads. Out came factory 115grn ball ammo. Still would not eject. So I went home, cleaned everything, still had issues. Of course now it was the weekend, so out came google. Apparently, this is a somewhat known issue where the cmmg system kills the ejector spring. this guy http://c3junkie.com/?page_id=954 has a long writeup about how he has struggled with it. He also has a thread going on about it on ar15.com, and many other guys have chimed in with silmilar issues.
I finally got to call cmmg, they confirmed that yes, I likely had a dead ejector spring and they shipped me 2 for free. They took about 2 weeks to come in and they are about .11 inch longer than the spring I pulled out of the bolt. New spring works great. 40 rounds no issues. Hopefully this new spring doesn't have any issues, but for now, my recommendation has fone from glowing to guarded (ha!) If you have a guard/banshee, I recommend you go ahead and call cmmg and get a couple springs send your way so you have them on hand if/when your's dies.
