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 Stuck Case in a DMPS
1Hailstorm  [Member]
11/6/2011 1:29:30 PM EDT
OK, Got a deal on a DMPS M4 5.56 1-9 twist. Found out why. It fires about 8 rounds then the case gets stuck. I was using reloads first trip out. Ok, could have been that. Second time out. Used factory stuff. It's not the ammo. The case rim is ripped off the cartridge case. The extracter looks good. I would say the gun has maybe 100 rounds out. No wear marks so it isn't broken in.

I have owned lets say a few AR's. But, before I whip out a drill and some polishing compund. I figured I would ask if there another fix.

On another issue. The rear sight was all the way left. I centered it and tried to zero it. Had to stop do to failure. I guess the front sight is off center.

I could contact DMPS and see if they will do anything about this. I could handle the sight issue. I put optics on alot of my rifles. But, I do like to know if I have to fall back to iron sights... That they work.

Just kinda feel like I got stuck in my zipper.
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Gatorhunt  [Team Member]
11/6/2011 3:55:04 PM EDT
I take it you did thoroughly clean the chamber with a chamber brush and a good solvent before firing it?

IIRC there were some others having problems similar to this with DPMS rifles and it was due to a tight chamber.

It's possible it might need to be reamed out to correct the problem but polishing might do it.

Dano523  [Moderator]
11/6/2011 5:20:41 PM EDT
DPMS is pretty good about bore sighting there rigs before they leave the factory.

So on that note, if the rear windage has to be cranked all the way over, suspect that the upper did not leave DPMS built, and DPMS marks their barrels as well, so if your barrel is unmarked, then then barrel may not even be DPMS to begin with.

Next on that note, if the rear sight has to be cranked all the way one side, then the barrel slipped in the upper barrel socket, and may be that the lugs are not cleanly unlocking from each other.

So, lets take the step back machine to if you have been correctly cleaning and lubing the rifle from the start (chamber brush by hand, and CLP used to lube the bearing upper surfaces), and see if that solves the problem. If not, then a send the rig back to DPMS to give it a once over to confirm that it's their parts, and correct everything if it is.
1Hailstorm  [Member]
11/7/2011 3:58:39 AM EDT
Yep, barrel marked DMPS 5.56 1-9 I was thinking about the slipped issue. I sent a email off to them and got a auto response saying the guy isn't gonna be in the office till mid month.....
So, I am gonna see what I can do till then. And I had a barrel wrench to. Sold it way back when...

I am one of those people who are anal about keeping their stuff clean. But, I think I will contact a local smith and see what the cost will be to fix it right. The bad thing is. Once you start playing around with these things. Makes me want to build more. I have done 4 and I know it is

I was a little concerded that maybe DMPS had a bad run of uppers or something. At least this stuff can be fixed. Thank you all for the knowledge. Yet again.
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sully  [Industry Partner]
11/8/2011 8:44:21 AM EDT
If you are ripping the lip off the brass, then you most likely have good extraction tension. Could be a maintenance issue, timing issue, rough chamber, too tight of chamber, bad ammunition, out of spec/worn parts, etc. What does the stuck brass casings look like on the front neck area and sides (pics are always helpful, as I am looking for deformities or marks that may give a visual clue)? Is this a new rifle, used barely, or used heavily? What type of buffer is in the rifle (look for markings on the front like an H)? What type of brass or ammunition? When the empty casing gets stuck, I am going to assume that you had to use a cleaning rod from the front end of the barrel to push the empty casing out, how hard was it to get the stuck casing out?

Greg Sullivan "Sully"
SLR15 Rifles
(763) 712-0123
1Hailstorm  [Member]
11/17/2011 5:50:05 PM EDT
The gun is new. I did check the cases. Looking for dents or scratches. Funny thing is. I contacted DPMS and I got a responce. Then nothing. Or, I can spend $25 and have it reamed and just shoot it.

As for ammo. The last trip out with PMC ammo. I fired three rounds. Then the case stuck. Put the gun away and fired guns that worked.
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