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Posted: 12/20/2008 11:40:04 AM EDT
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I have a new M & A Parts 20" Varmint Upper. I was disappointed to see that it came with a standard rifle barrel extension but an upper receiver with M4 cuts.
No big problem since I'll just swap it out and use the upper for a new build. I bought a standard upper and a YHM national match bolt, and replaced them out. I checked head space with a field gauge and the bolt didn't close. So I'm good there. When I put Brownell dummy rounds in they would feed OK, but the extractor claw wouldn't engage. The round was left in the chamber, and the next round obviously jammed. I tried the original bolt with the same effects. I fired the upper with the original bolt and the original M4 upper and didn't have extraction problem with live rounds. Is this a normal problem with dummy rounds or what should i do? Thanks in advance for your help. |
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I've tried both bolt carrier assemblies (Mil-spec and the NM). Both don't extract.
Both extractors had a rubber "O" ring in them. I tried them both without it and still no extraction. I'm starting to think it might be the barrel extension since BOTH bolt carrier assemblies failed to extract. Both of the ejectors have a lot of tension to them (they can be depressed however with some force). Should I remove a few coils from the ejector springs? Should I send it back to M & A Parts? Any ideas? I tried to take pictures but my camara can't do close-ups. sorry. |
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So you let the bolt slam home, it strips a cartridge off of the magazine, pushes it into the chanber, but the bolt will not lock into place? The only things I can think of with of off the top of my head are-
Is there an obstruction in the chamber or barrel preventing the round and or the bolt from locking in place? Can you push the forward assist (even if it's several times) will it lock with or with out a round? Have you tried dismantling then reassembling everything, in the off chance you did something wrong or left something misaligned? |
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I did a M4 build with a M&A kit this summer. The gun had intermitten faluire to extracts.
I replaced the extractor and the extractor spring with the lighter spring with a "BLUE" insert. The gun runs 100% now and the extraction pattern went from 1-2 oclock to 3-4 oclock, which I like better. |
| take the extraxtor out again, i had that intermittently happen and i couldnt figure it out for the longest time becuase i knew i had the correct parts and a d-ring in it so i never took it out. i evntually di and the pin was broken in half but the two halves stuck and and held the extractor in the bolt but just a little looser than it should have been. it would fire fine for hundreds of rounds then fail to extract a round. i kept a narrow steel rod with the gun and it was easily punched out. i used to shoot lots of wolf and blamed the ammo untill i finally disassembled the bolt for cleaning. |
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Everything's fine. The extractor, extractor spring, pin and o-ring all good.
It's brand new. Not a single thing wrong. Not even fired yet. (I'm trying to fix this problem first.) The only thing I didn't take off was the ejector, but it moves freely and has plenty of tension. |
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Ok here's the latest update:
I've tried just pushing the bolt into the barrel (without the carrier). With all the force I could apply the extractor doesn't engage. The front of the bolt sits on a rim around the barrel extension face. There's enough clearance from the locking teeth for the bolt to enter, rotate, and lock, but not enough room for the extractor to grab the case because of this rim. So, Is the rim normal? Should I get a new barrel extension? Is it possible for me to replace it myself? Should I just send it back and get a new barrel assembly altogether? What's my best option? |
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Ok here's the latest update:
I've tried just pushing the bolt into the barrel (without the carrier). With all the force I could apply the extractor doesn't engage. The front of the bolt sits on a rim around the barrel extension face. There's enough clearance from the locking teeth for the bolt to enter, rotate, and lock, but not enough room for the extractor to grab the case because of this rim. ._________________ ..........................| ........................./ ........................| <––-Rim ......................... ..........................\________________ ...................................................\_____ ..............................................................<––-Chamber ...................................................._____ ...........................________________/ ........................../ ........................./ ........................| <––-Rim ......................... ._________________| (Hope this crude drawing helps.) So, Is the rim normal? Should I get a new barrel extension? Is it possible for me to replace it myself? Should I just send it back and get a new barrel assembly altogether? What's my best option? |
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Here's an update on this extractor problem.
I sent it back saying I had an extraction problem and the receivers didn't match. M&A Parts Inc was great! They got it back to me in about a week with a new upper receiver and a new barrel. So I tried it out and to my dismay, the dummy rounds were still not extracting. I was upset to say the least. Until I realized something... The dummy rounds were the problem. I tried live rounds and sure enough the gun cycled with no problem. I feel like a dummy myself. But any way I'm very pleased with M&A Parts and NOT Brownells. |
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