cmmg upper problems

[ohlone]

i have cmmg conversion kit, got the same issue, it happens more often on the BDM mags, the cmmg factory mags got same issue but less often.... it didn't happen with the factory ones before (first 1500+ rounds), and it started recently after i started to use BDM mags, haven't found way to fix yet btw, i use federal bulk from walmart....

[ebencikiv]

I had the same problem as you AFTER I trimmed my mag to drop free. I got a new mag did not trim as much off and no more problem. The problem mag I put 1 wrap of electric tape around it and it works now, not 100% but about 95%. Good luck.

[joelukehart]

The feed lips should be around .240+ or -. I have an old Ceiner .22 kit with steel mags that I can adjust. I don't know what can be done with the plastic mags.

[shadow65]

Some of the BDM mags are too long on the feed lip area. The extracted round hits the feed lip on the way out and ends up in the bolt. You can trim the feed lip back slightly. I'm wondering if the CMMG feed lips are out of spec on recent mags.

[emERICa]

*edit* i'm home now and have uploaded pics. pretty sure it's the mags now i just need to figure out why they are making the last (sometimes second or third to last) round stand straight up. did it with federal bulk 550 pack hollow points as well as with cci mini mag solid round nose bullets. please help on what to do about the mags really don't want to buy more and would like to be able to use this at an appleseed at the end of the month and would rather not have to send my mags back to cmmg. i trimmed the mags to where they dropped free which means they move around a tiny bit in the mag well but no more than my 5.56 mags do

First day at the range with a new dedicated upper and the last round always gets jammed in the bcg. Its getting pinched at the top. Between the stainless bolt carrier and the collar that has the feed ramp on it but at the top not where the feed ramp is. Its like the rounds are feeding straight up. Does it with both fed 550 and cci mini mags with two diff cmmg10 round mags. Pics to follow I'm still at range trying to figure this out.





this is how the mags had been coming out if i eject them before they jam. now that i'm looking at the pic it looks like the mag is flipping me off. well f**k you too buddy




this is not a typical malfunction only happened twice unlike the other type which got jammed in the bcg (first pic)

Same EXACT thing was happening to me. The last round would almost always stovepipe into the chamber and get stuck with my CMMG mag. I bought some BDM mags and my feeding issues are gone.

[paintballdad]

psubond, where are you located? If you're in my area, i have some BDM mags we can try out to see if your problem is mag related. LMK.

[psubond]

i'm in lemoore near fresno

[triplestack3]

I had the exact same problem. It's the magazines. I tried using three different types of ammo and kept having the same problem. Had to send my mags back to CMMG and buy some BDM's. Have had zero issues with the BDM's and they are the new glass filled style.

[mskochinski]

No no no, call CMMG and get the new mags they produced. Same issue with mine, including the BDM's and CMMG sent me new mags with Black followers and not green. The problem was with the lips on top of the mag, 10/30, not being strong enough. They re-casted them like the 30 mag and now they are just fine. It should never stick straight up like that.

[psubond]

talked to CMMG today and they are sending me some of the evolution gen 2 mags with metal followers. when i get them i'll be sending the defective mags back so all is well no harm no foul other than a bit of frustration at the range. easy to deal with customer service thanks Chris!