Topic: DPMS CMMG PROBLEMS (Read 4669 times)

the bigness · « **on:** August 28, 2010, 09:22:58 AM »

Hello I have a cmmg lower with bb and 10/20 magpul mags.After 200 rounds 40 of them bent and mangled today @ the range I realized when I hold the mag up while shooting no feeding problem.This is driving me crazy man.The upper is DPMS
Doesnt Provide Multiple Shots:) Have you guys had any problems with this combo? After spending $3000.00 on magpul everything/jard/enidine/fws30 comp./eotech combo I would like to have a shootin gun not a single shot lookin gun.
What you got? I appreciate any help. Thanx Jim

Matt.Cross · « **Reply #1 on:** August 28, 2010, 06:54:57 PM »

Sounds like the problem could potentially be the mags themselves. Are they new? A worn magazine catch is the only reason I can think of why your mag problems go away whenever you shoot with the mag pushed in. Check your mags and your magazine catch for wear that could be problematic. I've also heard of people having problems when their mag catch was one turn too loose.

the bigness · « **Reply #2 on:** August 28, 2010, 06:59:16 PM »

I'M USING 10 BRAND NEW P-MAGS (10/20) IN ROTATION

imschur · « **Reply #3 on:** August 28, 2010, 08:59:54 PM »

What is a "bb"?

Are you saying that the first 200 rounds were good then the next 40 went to crap or 40 out of 200 bent and it was all a bad experience?

Did you assemble this yourself?

Is it short stroking?

When you get a good run does the bolt lock back properly after the last round?

98Z5V · « **Reply #4 on:** August 28, 2010, 09:24:21 PM »

Quote from: Matt.Cross on August 28, 2010, 06:54:57 PM

I've also heard of people having problems when their mag catch was one turn too loose.

This part is a big deal on the .308s, because the mag catch parts are all AR-15 spec stuff. They have to be turned in just right on the .308 (not flush, but not too far from flush with the button), or they'll turn into a problem later - if not a problem from the start.

May not be the exact problem the OP is having, but it's something to check out.

I was wondering about the "bb" reference, too.

98Z5V · « **Reply #5 on:** August 28, 2010, 09:30:13 PM »

Quote from: the bigness on August 28, 2010, 06:59:16 PM

I'M USING 10 BRAND NEW P-MAGS (10/20) IN ROTATION

10/20 - you using 10-round conversions from some company, but all P-MAGs? Bent and mangled rounds (feeding problem) can be caused by mag springs that are WAY too strong, but I haven't seen anything like that from a new 20-rd P-MAG so far. Not even brand new ones, outta the wrapper and loaded at the range.

It can also be from the BCG short-stroking, like imschur asked about. That's gonna come from a gas problem, or a buffer/buffer spring problem.

survivalshop · « **Reply #6 on:** August 29, 2010, 03:38:09 AM »

Try loading the P-mags to the full 20 rounds & letting them set that way for a few days to a week . I had the same problems with my CMMG lower as far as feeding (no mangled rounds ).
The CMMG lower just did not like the P-mags at first until I seasoned the mag springs with a full loading an setting aside for a week .
Mine all function fine now .

The DPMS & C Product mags worked fine .

Look in the Generial section under "16 " barrel with rifle length gas system ".

I have a CMMG lower with a SI Defence ,Gen. II billet upper.

TacBlade · « **Reply #7 on:** August 29, 2010, 10:08:03 AM »

survivalshop, can you PM me what your whole setup is? I am doing the same thing, except not the GEN II upper. Thanks

the bigness · « **Reply #8 on:** August 29, 2010, 12:56:00 PM »

BB-bullet button Stupid california compliance thing 10/20- 20 round pmags modified to only hold 10 another calif/compliant....

the bigness · « **Reply #9 on:** August 29, 2010, 01:00:52 PM »

The first one goes bang then the second bullet the bcg rides over push toward feed ramps and gets the grind.When holding the mag
while shooting and pushing up slightly full mag dump.Bolt locks back after good run.

98Z5V · « **Reply #10 on:** August 29, 2010, 01:15:02 PM »

Ah, I forgot about the bullet button crap you have to deal with. I'd look there first - at the mag release setup, and how the bullet button is threaded onto the mag release. If you're able to hold the mag in a position to make it feed accurately/correctly, that's gotta be an indication that the mag release isn't holding it into the proper position (when you're not gripping the mag). Make sense? I think I confused myself, trying to explain that...

Edit - what's happening to your gun is called "bolt over ride." Some Google searches on that term should give you some decent results, and maybe how others have solved it.

the bigness · « **Reply #11 on:** August 29, 2010, 02:16:12 PM »

Thanks for your help I will check bolt over ride threads. I'm goin out to the range in a few.I converted a siaga 308 to AK platform and this thing shoots any ammo all the time bone dry.I can see why all these hard core survival guys have a back up AK just in case
they are crude but they seem to work 100% of the time.So if I fight this AR and it gives me grief this fire breathing AK308 should keep me from going into AR depression mode.

survivalshop · « **Reply #12 on:** August 29, 2010, 05:24:58 PM »

Yes , the bullet button could need some tweeking to get the mag high enough or stable enough to feed reliably.
Might also look deeper in to your mag conversion .( 10/20 )

the bigness · « **Reply #13 on:** August 29, 2010, 08:25:05 PM »

Well back from the range w/dpms.cmmg 308 and after shooting radway green 762 and british delinked ammo (both NATO) NOT ONE MIS FEED BUT I'M STILL HOLDIN ON TO THE MAG LIKE A GRIP POD!(have to push mag up for for the other 9). The AK308 which I found is discontinued ran without a hitch,as I new it would.
Funny thing happened @ the range today.My back was turned to the targets 100/200/300/400/5/6 and I hear the range master
call a cease fire.He said animal on the range! I turned around waiting to see a squirrel or on the outside a raccoon but no, to everyone's surprise it was F@%$^*# 3 deer one buck and two smaller! Now to a lot of folks this is probably an everyday scene but being 35 min. from LA is pretty wild,for wild life.I hope someone caught video. Walking @ 300yrd mark Now I want to shoot animals. The fine would be poaching/felony/$10,000 dollar fine California is a great place to live but ya wouldn't want to shoot here. Oh yeah I LOVE ANIMALS AND BAMBI BUT IF THEIR STUPID ENOUGH TO WALK THROUGH A RANGE W.50BMG AND A GRIP OF SHOOTERS THEY WILL DIE AND I WILL EAT THEM!http://308ar.com/forum/Smileys/default/grin.gif