CMMG 22 upper jamming

[Rentz]

First chance ive had to really take out my 22 ar i built using a dedicated cmmg upper and the first few mags were great then the problems happened, every 1-2 shots it jammed.

Looked like the spent casing wasnt ejecting out it was getting stuck in the upper, and when it did eject the problem was the new round coming up at an angle and then bending and jamming

anyone had similar issues? I did some reading and all i really found was suggestions to polish feed ramp, etc

 

[matefrio]

I clipped a few coils off mine and resolve this issue for the most part. I still have problems on occasion of a shell case getting stuck up in the charging handle with mine.

 

[Rentz]

I clipped a few coils off mine and resolve this issue for the most part. I still have problems on occasion of a shell case getting stuck up in the charging handle with mine.

Off the buffer spring?

 

[matefrio]

Off the buffer spring?

yep. a good resource to troubleshoot the system:

ST-22 & .22LR Conversion Kit: tweaks for feeding problems - AR15.COM

http://www.ar15.com/archive/topic.html?b=2&f=282&t=168048

 

[Jon Payne]

I had the same problem with some new Blackdog Mags. When I began using the older feed lip design it solved the problem.

 

[Rentz]

Thanks guys going to try shortening the buffer spring and polishing the feed ramp some
i did notice looking today it doesn't look like the charge handle fully locks back in after cocking each time. Have to push it in some

Also could be I didn't fit the cmmg mags well, but they look properly seated

 

[Rentz]

started off by cutting 2 coils off the recoil spring, need to get it to the range this week to test it out but just dry running it pulling the bolt back the action seems smoother. the bolt has returned fully each time, before i would have to push the charging handle in some which i thought was odd.

A guy at the range last week said he had the same issues with his 22 upper and he cut some coils and it helped some but was never 100%

 

[Rentz]

think i finally fixed it. cut a few coils on the spring and that seemed to cycle magazines better but rounds would still get jammed and bent in the chamber.

Ordered 2 blackdog magazines and buzzed the chamber and it worked great, went back to the cmmg mags to test and it became a jamo-matic again.

so the simplest fix ended up being the solution, new mags

 

[ChunkyMonkey]

I've had similar issues with a piston upper from CMMG, it's a 223/556 but every other round I'd have to push the forward assist and I'd feel it go forward about 1/8th inch. If I did that, it would always fire. If I tried pressing the trigger without the forward assist, then I'd get a light strike.....