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Posted: 2/26/2008 10:23:30 AM EDT
hey, i have just started having a feeding problem in my ar.i think it is a mag problem but i wanted to check with yall first. when i charge the weapon the bolt is only able to feed the round about half way out of the mag. i can pull the bolt back and let it go and it will feed the round the rest of the way in. i thought i must have been just riding the charging handle, but then the same problem would happen while firing. the bolt picks up the round in the mag but is unable to get it out of the mag and into the chamber. the front of the bullet stops at the m4 feed ramp. it does not look like it is hanging on the feed ramp. it seems like it is getting stuck on the feed lip of the mag and the front wall of the mag. the casing comes out all scratched. it happens through the whole mag not just the first few rounds. the weapon works fine with other usgi mags. the mags it has the problem with are c product aluminum mags with magpul gen 2 followers and black marlube finish, i have 15 of them and have not tried all of them. i tried a 9mm buffer thinking it needed a little more momentum to get the round out, but that did not help. the rifle is a dpms lower and a lmt 10.5 with lmt bcg. buffer and buffer spring came with the vltor stock. i think it is a standard buffer. the ammo is 55 grain wwb and 75 grain 556 tap. i compared the problem mags with some known good ones. in the problem mag the rounds seem to sit a little bit lower then in the good mags. the round does scape the front wall of the mag. i guess it is a mag problem, but i figured these mags should be great. has anyone eles have any problems from these mags. i already called 44mag.com and they said they would be happy to trade them out for other mags they sell. i just wanted to see if any one else had any ideas. thanks james
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hey, thanks for all the help. im starting to think it may not be all because of the mags. i did look at them real close and they do have burs on the feed lips, but today i shot with some of my old mags and i was getting the same problem. the round is only able to make it about half way out of the mag. i think i may need a new or heavier buffer spring, and maybe a heavier buffer too. i have probably close to one thousand rounds through it. do yall have any other ideas. im going to loan my old and new mags to one of our firearms instructors to use in a rifle class to see if he has any problems to try to rule out the mags. i may have a chance to try an h buffer and i think i can find a new spring somewhere. any help would be great. thanks. james ps the first 500+ rounds through this gun have been flawless. this problem started only happining when i first charge the weapon, so i thought it was me riding the charging handle, but it has just started happening during firing. thanks again. |
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thanks dano523. ok i just now got around to messing with this thing. it is not the mags. i get the same problem with all of my mags. i tried the same lower with another upper and the same mags and it was 100% so the problem is the upper. i looked in side while a round was stuck and it looked like the round may be getting stuck on the m4 feed ramp. it happens mostly on the left feed position but sometimes on the right. their is a nothch that is cut in both feed ramps that the point of the bullet is wedging between. when i get the bullet out there are two gouges in the bullet right about where the edge of the notch in the feed ramps are contacting the bullet. i guess i could try to file down the sharp edge. i dont see why its having this problem now, it went almost 1000 rounds with no problem. atleast i know its not my sbr lower or mags. anyone have any ideas? i dont want to start filing on the inside of the gun but it looks like thats the problem. i got the upper directly from lmt so i guess it is under warrenty, i just hate sending stuff back. thanks again, james |
10.5's can be temperamental beasts. Read the "Urgent...." tacked thread. Look at the forward side of the barrel extension lugs and the rear side of the bolt lugs to see if hard unlocking has wiped a burr up and out into the feed ramp path. Do you have the 10.5" free length buffer spring and proper 10.5" barrel carbine buffer? Using the DPMS lower as a gage, mount some loaded mags, both old and new, and see if you can tell any difference in the distance perpendicular from the top of the mag well (lower-upper parting line) to the tip of the top bullet in the ammo stack. I have had problems with newer mags holding the bullets lower than the older ones. |
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hey, thanks for all the help. the rounds in the new mags do sit a little lower then my old mags, but they do function 100% with my other upper. both old and new mags ftf with the lmt 10.5. im pretty sure it is a burr in the feed ramps/locking luggs. with the upper off the lower i can run a round up the fed ramp by hand and get the tip to stick in the slot on the on the feed ramp. i sent lmt an email and they called less then an hour later. they said to either try to clean up the feed ramp with a file or if i did not want to do it i could send it back andthey would take care of it. i do have a standard buffer, i never switched to an h buffer because it worked so well. do yall think an h buffer will help prevent another burr from forming? do yall think i should try to file it my self, i could not see a burr inside but a do see some shinny spots on the corners of the ramps where the round is catching. i might should just send it back for them to fix it. thanks for all the help. james
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While you are talking to LMT, you might inquire which spring/buffer they recommend for a 10.5" carbine. There is now H, H2, and H3 available, one tungsten two steel wts; two tungsten, one steel wts.; and three tungsten wts, respectively. My 16" carbine runs a 10.5" free length .072" dia. wire spring and an H buffer. I only point that out to say that if 16" carbines are already H, then the 10.5" carbine probably should be H2 or H3. Also check out this thread: www.ar15.com/forums/topic.html?b=3&f=66&t=362596 |
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i think i may have fixed it!!!! as lmt suggested i used a file to smooth out the sharp corners on the slots on the feed ramps. it now hand cycles 100% with all of my mags(11 c-products, 10 ok, 8 center, and 4 colts). thanks for all of the help guys. i think i will still try an h2 or h3 buffer since that is what lmt suggests. thanks again, i will post again after i go to the range. james 
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