PDA

View Full Version : cmmg upper problems


psubond
09-10-2011, 3:55 PM
*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.

http://i167.photobucket.com/albums/u147/psubond/IMAG0219-1.jpg

http://i167.photobucket.com/albums/u147/psubond/IMAG0220-1.jpg

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 :mad:

http://i167.photobucket.com/albums/u147/psubond/IMAG0221.jpg


this is not a typical malfunction only happened twice unlike the other type which got jammed in the bcg (first pic)
http://i167.photobucket.com/albums/u147/psubond/IMAG0222.jpg

Packy14
09-10-2011, 4:05 PM
this happened to me when my mags were failing, check the mags

psubond
09-10-2011, 4:06 PM
Brand new mags. What should I be looking for to check?

shadow65
09-10-2011, 4:28 PM
It's the mags. Do you have access to any BDM mags?

psubond
09-10-2011, 4:29 PM
Will have to order some. Almost feels like the spring is too weak in the two mags I have

shadow65
09-10-2011, 4:48 PM
Did you adjust the mags for fit in the mag well?
Also, make sure the bolt is closing all the way and not dragging on the bolt catch.
Dave N

shadow65
09-10-2011, 4:50 PM
Shouldn't have anything to do with spring pressure. The standard mags don't require the same pressure the BHOA do.
We will get it straightened out. I hate that your first range trip results in problems. Wish I was there to fix it.
Dave N

psubond
09-10-2011, 4:59 PM
They fit about the same as my 556 mags. Trimmed them like paper said that came in box

capitol
09-10-2011, 5:27 PM
dude dont worry too much because I had several issues with my cmmg upper at first, but after a lil tuning here and there my rifle is running great!

tip: it's the mag :facepalm:

psubond
09-10-2011, 5:42 PM
What did you do to fine tune it?

xbimmers
09-10-2011, 5:46 PM
I had the same issue when I used Blazer 22LR...it seemed the coating on the lead bullet was gumming up the action. I switched to Federal and have NO problems at all!!!!!!

What ammo are you using?

shadow65
09-10-2011, 7:01 PM
I still think it's a bad mag. The same thing will happen if the feed lips are worn.
If you have somewhere close to pick up a BDM mag, grab one. It should work fine and give you something to shoot until CMMG gets the mag taken care of.
Do you have more than one CMMG mag? Are both the same?
I suspect the feed lips are out of spec.
Dave N

psubond
09-10-2011, 7:04 PM
yea i have two. both are doing the same ****

psubond
09-10-2011, 7:09 PM
will the mags for a S&W or colt work with cmmg upper/stag lower?

xbimmers
09-10-2011, 8:45 PM
Shadow, I was having the same issue with all my BDM (Black Dog Machine) mags during the first 100-150 rounds. I have the stainless bolt and collar. I couldn't go through 10 rounds without a failure. It was really pissing me off. I stopped using the Blazer ammo and went with Federal bulk. All is well now.


I still think it's a bad mag. The same thing will happen if the feed lips are worn.
If you have somewhere close to pick up a BDM mag, grab one. It should work fine and give you something to shoot until CMMG gets the mag taken care of.
Do you have more than one CMMG mag? Are both the same?
I suspect the feed lips are out of spec.
Dave N

ohlone
09-10-2011, 11:32 PM
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
09-10-2011, 11:55 PM
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
09-11-2011, 1:55 AM
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
09-11-2011, 8:00 AM
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
09-11-2011, 5:22 PM
*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.

http://i167.photobucket.com/albums/u147/psubond/IMAG0219-1.jpg

http://i167.photobucket.com/albums/u147/psubond/IMAG0220-1.jpg

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 :mad:

http://i167.photobucket.com/albums/u147/psubond/IMAG0221.jpg


this is not a typical malfunction only happened twice unlike the other type which got jammed in the bcg (first pic)
http://i167.photobucket.com/albums/u147/psubond/IMAG0222.jpg

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
09-11-2011, 10:53 PM
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
09-11-2011, 11:46 PM
i'm in lemoore near fresno

triplestack3
09-12-2011, 11:31 AM
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
09-12-2011, 5:19 PM
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
09-12-2011, 6:13 PM
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!