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Posted: 6/10/2010 7:44:56 PM EDT
| Put a DPMS DCM Gun together for a friend using a complete upper from dpms with a lower that I put together. The rifle will not feed from the right side of the magazine, and only the right. It will feed fine from the left, but when it feeds from the right, the case is getting stuck only about 1/4 forward from its resting place in the magazine, with the bullet lodged in the feed ramp/bbl xtension, and it appears as if the case mouth is stuck on the forward most point of the feed ramp. Has any body ever had this happen, or know a fix other than sending back to dpms?? |
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I imagine you are using USGI mags. My guess is that one of the lips on your mag may be lower than the other causing the righthand round to feed off the mark. When I fired my 1st AR (with M4 ramps) I used several H&K used ex-Marine Corps surplus mags. All fed great except for one. I set it aside, then inspected it once I got home. What I found was the rounds sat lower in that mag than the rest. Taking out the BCG, I put a full mag in the rifle and hand stripped the rounds to watch how they feed along the ramps into the chamber. Sure enough they either hit on the receiver or the leading edge of the shell caught on the front of the mag. measuring how high the point of the bullet sat above the front of the mag, it was about a 1/16th of an inch. I then looked at the lips and how the rounds made contact with the mag lips. I noticed that the front or leading edge of the mag lips were bent down and were holding the round nose down in the mag. I then reasoned if I straighten the lips the nose of the round would nose up making the round sit higher during feeding. I bent the lips up so the bullet point was at least an 1/8th of an inch above the front of the mag. The round should touch all along the length of the lips. I paced the mag back into the rifle and fed the rounds by hand again. This time the rounds hit the ramps every time. This height setting should work with rifle ramps, I tried a tuned H&K mag in one of my A2 rifles without a hand feed issue. I also checked a Pmag in my A2 and it fed as it should with rifle ramps.
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| Yes, the right side does look a hair different than the left. It actually looks like they forgot to make a certain cut, after i compared it with a few of my rifles. It is a NRA service rifle gun, so we are shooting 69 and 77 grn noslers and sierra match bullets out of the magazine, and these are the ones that we have problems with. I tried running a few 55 grn fmjs through it, and they fed, however they are still hitting the bbl extenstion hard because the are pushing the bullet back anywhere from .010 to .09, and those are crimped m193 rounds. You can also tell that the bolt doesnt close on the 55's as hard as it should. I think we are just giong to send it back to dpms. That will be the most definitive way to get it fixed, im just kinda mad cuz the next high power match is june 26th, and I doubt dpms will fix and return that fast. |
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Sorry,
Basement hacking with a chain saw file is not a option for me since I do have mills and lathes with do make such work clean and fast. But lets step back a bit and take a closer look at the rig as hand. Running MK262 type ammo, The only time he will be coming out of the mag is for rapids. Now come the fact that he is coming out of the mag for such, is the barrel throat'd for such ammo, being that he is not having a huge jump to lands when the OAL of the round is to fit/come out of the mag? If yes a long jump, then a bullet with a shorter ogive would be more accurate when having to mag run (even going to a flat tail design), and just sled for the longer ranges with the bullet long loaded to achieve a less than .003 jump since you have more time for such during the shot strings. |
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Quoted:
Put a DPMS DCM Gun together for a friend using a complete upper from dpms with a lower that I put together. The rifle will not feed from the right side of the magazine, and only the right. It will feed fine from the left, but when it feeds from the right, the case is getting stuck only about 1/4 forward from its resting place in the magazine, with the bullet lodged in the feed ramp/bbl xtension, and it appears as if the case mouth is stuck on the forward most point of the feed ramp. Has any body ever had this happen, or know a fix other than sending back to dpms?? Send it back to DPMS . God bless Wyr |
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