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Posted: 1/5/2009 4:34:30 PM EDT
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I recently put together my first build.
It is a: BCM 16"Middy Upper BCM BCG CMT Charging handle Spikes Tactical Lower Stag LPK BCM Buffer Tube w/ Standard buffer Today was my first day shooting this rifle. The problem is that every 5-7th round will partially feed. The round goes far enough into the chamber that you can engage the trigger, but the firing pin leaves no mark on the round. I tried smacking the crap out of the forward assist but the round would not budge. To eject the round I would have to bounce the but stock off the groun while pulling on the charging handle. I was using reloads (These have been 100% in my LMT and Bushmaster) and Bravo Comapany, USGI and Bushmaster Facotry magazines. |
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Quoted:
The round goes far enough into the chamber that you can engage the trigger, but the firing pin leaves no mark on the round. If I interpret this right, the round is fed into the chamber, but is not going far enough forward that the bolt can lock. Your cartridges do not fit your chamber. Either they are made incorrectly, or the chamber is. |
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When I would smack the butstock off the deck it took quite a bit of force to eject the round.
The reloads are LC brass thats only been fired once. There are all in spec and have never presented any problems in other rifles. Tomorrow I will be going out to do some testing. I will try the BCM upper on a LMT lower (has been 100%). Ill try the Spikes lower on a LMT Upper (Has been 100%). I will also only shoot LC/UMC factory ammo and use PMAGS. Any thing else I could be missing? |
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Quoted:
When I would smack the butstock off the deck it took quite a bit of force to eject the round. The reloads are LC brass thats only been fired once. There are all in spec and have never presented any problems in other rifles. Tomorrow I will be going out to do some testing. I will try the BCM upper on a LMT lower (has been 100%). Ill try the Spikes lower on a LMT Upper (Has been 100%). I will also only shoot LC/UMC factory ammo and use PMAGS. Any thing else I could be missing? Remember to only change one thing at a time, so you can identify where exactly the problem lies. |
| If head space specs out ok then the chamber may be a bit tight as well. I know on my Olympic (not the best I know) it had a couple FTE the first time out until I ran a few rounds through it and things loosened up...after that it's been golden. My Oly is ~9 yrs old and Oly told me their chambers were a bit tighter than most, which I found out for myself. Use a cleaning rod topush out the FTEs, better than banging it on the ground. HTH |
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Grab a couple of the rounds that did not chamber in the rifle you built and try to chamber them in the LMT. If your loads have been reliable in the past and they still chamber in the LMT, the BCM may be a little tight or the LMT may be a little loose for your handloads.
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Quoted:
When I would smack the butstock off the deck it took quite a bit of force to eject the round. The reloads are LC brass thats only been fired once. There are all in spec and have never presented any problems in other rifles. Tomorrow I will be going out to do some testing. I will try the BCM upper on a LMT lower (has been 100%). Ill try the Spikes lower on a LMT Upper (Has been 100%). I will also only shoot LC/UMC factory ammo and use PMAGS. Thats a damn good approach to try and isolate the problem. If the once fired brass is within spec I would suspect first it's a tolerance issue in the chamber; either too tight or headspace outa spec. Might also check the primers on the fired brass and see if you had excessive pressures. A GOOD gunsmith may need to make one more pass through the chamber with a reamer. |
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