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9/22/2017 12:11:25 AM
Posted: 11/16/2003 6:12:14 PM EDT
I read a few months ago how some DMPS made 14.5" and 16" M4 type uppers were having a rash of failure to extract problems, particularly sold through CMMG. Not a bash on CMMG, since I heard they went to great lengths to set things right. But, did anyone here experience or come across this?

Thanks

Ben
Link Posted: 11/16/2003 6:37:52 PM EDT
Only problems I've ever had with my CMMG/DPMS M4 uppers (I've got five different ones, anything from 16" to 10.5") has been with Radway Green ammo. Lake City, PMC, and S&B ammo has always worked fine. Call John or Jeff and they will take care of you. They are the best!
Link Posted: 11/17/2003 2:39:06 AM EDT
Never had a problem with mine.
Link Posted: 11/17/2003 6:18:00 AM EDT
[Last Edit: 11/17/2003 6:20:52 AM EDT by Yojimbo]
My 16", 1/7 M4A3 upper has been flawless so far! [img]http://www.hunt101.com/img/061255-big.jpg[/img] See the link below for the reliability test I ran shortly after getting it. [url]http://www.ar15.com/forums/topic.html?b=3&f=12&t=164401[/url]
Link Posted: 11/17/2003 6:56:53 AM EDT
My first two rounds failed to extract. Not a single malfunction in about 650 rounds since.
Link Posted: 11/17/2003 7:09:57 AM EDT
I e-mailed them about this 'issue'. From what I understand, very few (4 was the number IIRC) actually had any problems out of the whole batch.
Link Posted: 11/17/2003 8:15:22 AM EDT
I have two of these barrels and only one gave me any any failure to extract issues and that was using Wolf ammo [:(]
Link Posted: 11/17/2003 11:13:20 AM EDT
[Last Edit: 11/17/2003 11:46:23 AM EDT by wyv3rn]
I had numerous problems with mine. I "fixed it" by polishing the chamber. I haven't had a failure to extract since. Fixed is in quotes however because the rifle will still deforming case rims pretty badly. This means it was operating on the edge of reliability. The rifle was getting too much gas, I slowed down the action by replacing the DPMS BC/B with a Colt M16 BC/B which is heavier than the DPMS BC/B that came with it (dremelled back the autosear contact point though) and using a Colt "H" Buffer. Now every single case rim has nothing more than a pretty little extractor mark. And to make sure I wasn't operating on the edge of reliability in the other direction (too slow of an action), I used some really down-loaded ammunition, aligned the gas rings and closed the ejection port cover. Basically did everything I could do to create more drag/resistance on the action. I've even fed the rifle rounds I intentionally dropped in dirt and sand. Everything extracted great. I wouldn't stray from CMMG/DPMS if: 1. I needed a 16" 1/7 M4 profile barrel. 2. I was on a budget. If I needed a 14.5" 1/7 M4, I'd probably try to get a Bushmaster first. If I wasn't on a budget, I'd get a Colt barrel. No matter what I chose (but especially if I went with the DPMS), I'd get a Colt M16 BC/B. Save your money and don't buy others' BC/Bs. Also, I am glad that I had these problems to start with. Troubleshooting these problems has heavily contributed to helping me gain an intimate knowledge of the AR15 operating system through each step of a cycle and each parts' purpose. The problems (along with paying attention to detail) also have given me failure-points-of-reference and have helped me to develope a very reliable rifle that I can be confident has high margins for error. EDITED TO ADD: The total numbers of failures to extract BEFORE the fixes and INCLUDING the rounds dropped in dirt numbered less than 10. EDITED TO ALSO ADD: Oh, and my barrel came apart from my upper very easily; by hand when I was re-indexing the FS. I think they failed to re-tighten 3 times, or tighten down to at least 30ft-lbs. Either way, I had to re-assemble it and if I were to order another prebuilt upper from CMMG/DPMS again, I'd take it apart and re-assemble it myself just to be on the safe side. EDITED [b]AGAIN[/b]: I must also add that this upper has been tops in accuracy and continues to be after all the fixes. Here is the link to the complete thread regarding this rifle. It has been out a couple more times since my last post. The rifle is still functioning flawlessly and leaving beautiful case rims behind with no signs of even remote problems to be found. [url]http://www.ar15.com/forums/topic.html?b=3&f=12&t=169340&w=searchPop[/url]
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