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DPMS/CMMG feed jams...HELP!!!

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12 years 10 months ago #9711 by why2dogs
DPMS/CMMG feed jams...HELP!!! was created by why2dogs
Bought my first AR10. Assembled and unfired. DPMS upper chambered in 7.62 x 51. DPMS SASS barrel/bolt, DPMS chrome bolt carrier. CMMG lower with DPMS parts kit. Rifle came with 3 Magpul Pmags. The rifle will NOT feed. Jams on every round and ruins the round in the process. Any compatibility issues with DPMS/CMMG/Magpul? Please help! Thanks!!!

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12 years 10 months ago #9730 by LebbenB
Replied by LebbenB on topic Re: DPMS/CMMG feed jams...HELP!!!
First, I'm sorry that you're not having a good experience with the rifle. It's very frustrating, I know.

A couple of questions:

Does the malfunction occur with every magazine you use?

What part of the cartridge deforms - Bullet nose, bullet body, the case or all three?

How much lube are you using on the bolt/bolt carrier?

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12 years 10 months ago #9732 by why2dogs
Replied by why2dogs on topic Re: DPMS/CMMG feed jams...HELP!!!
Relpied about an hour ago with posted pics, but it never showed up? Trying again without pics. I have three new Magpul Pmags. Tried all three with two different brands of .308. Winchester and Hornady. Jammed with every combination. Called Magpul and they say no compatability issues with their mags and CMMG lowers. Rounds suffer damage to all three points. Bent/smashed noses, scratches on the sides of the projectile and dented and scratched casings. The BCG was loaded with lube (red...looked like light grease). Seemed excessive, so I mopped it out before hitting the range, but left a nice coating on all mating surfaces. Rounds jamming between the bolt and the feed ramps. Suspect there may be a feed ramp issue. I'll try to upload some pics again after this post (damaged rounds and feed ramps). Might have to wait till I get home. Wireless may be a little slow for picture uploads. Anything else you can think to ask, PLEASE do so. Thanks for your reply, Dave.

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12 years 10 months ago #9739 by LebbenB
Replied by LebbenB on topic Re: DPMS/CMMG feed jams...HELP!!!
Good data. The reddish grease could be preservative. Clean all of it off the BCG and everywhere else it is, then lube it with a high quality liquid lube. Try cycling it by hand and see if the problem persists. If it does, based on your description of the damaged rounds, I agree that the feed ramps might not be in spec.

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12 years 10 months ago #9741 by Charlie
Replied by Charlie on topic Re: DPMS/CMMG feed jams...HELP!!!
From Magpul's website:

The 7.62x51 NATO (.308 Winchester) PMAG 20LR is a lightweight, cost effective, high reliability magazine for SR25/M110 pattern rifles* featuring true 20-round capacity, constant-curve body, and snap on Impact/Dust Cover. Designed specifically for military-issue MK11/M110 rifles and mil-spec ammunition (including M118LR), the PMAG 20LR is less than half the weight of standard issue steel magazines and maintains a service life round count approximately equal to the rifle barrel itself.

Do the DPMS upper and CMMG lower both fit the description of SR25/M110 pattern rifles? If not I bet it's a mag and/or feedramp issue.

Charlie

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12 years 10 months ago #9748 by why2dogs
Replied by why2dogs on topic Re: DPMS/CMMG feed jams...HELP!!!
Hello Charlie. I spoke with a tech rep from Magpul. He said these magazines will work just fine in my application. They will NOT fit the Armalite AR-10 or M14/M1A. I plan on ordering a steel mag from DPMS anyway, but I'm leaning towards the feed ramps. DPMS said they would take a look at the upper. I'll have to pay because the upper was assembled with all DPMS parts...BUT....not by them (built by the person I bought the rifle from). If I send it to them, I guess the worst thing they could say is that there is nothing wrong with it. If there is a problem, they would be the ones to correct it. Wish I could get a good picture of the ramps. They really look funky to me. I'll keep my progress posted. Thanks!!

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12 years 10 months ago #9749 by why2dogs
Replied by why2dogs on topic Re: DPMS/CMMG feed jams...HELP!!!
Cleaned and lubed the BCG and upper receiver. Still had issues cycling by hand. Rounds were getting lumped up to the point where I had to use the forward assist for the extractor to hook on and had a hard time pulling back on the charging handle to extract the round. Plan on sending the upper to DPMS to get it checked out. Will let you know what they say. Thanks

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12 years 10 months ago - 12 years 10 months ago #9752 by why2dogs
Replied by why2dogs on topic Re: DPMS/CMMG feed jams...HELP!!!
Feed ramp pic
Last edit: 12 years 10 months ago by why2dogs. Reason: pictures won't upload

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12 years 10 months ago #9753 by why2dogs
Replied by why2dogs on topic Re: DPMS/CMMG feed jams...HELP!!!
Pics not uploading

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12 years 10 months ago #9759 by Charlie
Replied by Charlie on topic Re: DPMS/CMMG feed jams...HELP!!!
Here's the pic of why2dogs feed ramp.

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He writes "Pay particular attention to the orientation of where the two feed ramps meet, They don't look as if they come together at "6 o'clock". To me; it looks like they didn't finish the ramps at the factory."

Charlie
The following user(s) said Thank You: why2dogs

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