AR Sponsor
Posted: 3/12/2007 5:29:05 PM EDT
I bought my son a BM AR about two years ago. We have five ARs in the family and from day one his short stroked. Took it back to the gun shop and they checked it out and said it was fine. They said it was probably fussy about ammo & it would work itself out. Well that was about 5k rounds ago and it still short strokes on anything but XM193 or M855. The gas tube seems fine, the gas rings are fine, the rifle is cleaned, lubed and maintained properly, I changed the buffer out of another AR, swapped the bolt and it still shorts strokes on anything but XM193 or M855. The other BM & Colt ARs function on anything I put through them but this POS is fussy as hell. I am ready to send it to BM and tell them to shove it. Any ideas of how to cure this or what could be causing it? With XM193 & M855 getting scarce I really need a cure. Thanks in advance. 
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| My BM was shortstroking on me a while back....after almost losing my mind trying to figure out the problem, I realized that the Carrier Key bolts weren't properly staked and the bolts walked themselves loose. Check yours and make sure the carrier key bolts are tight. |
| I would tend to think maybe the gas port is undersized if from day one any ammo loaded lighter than XM193 or M855 causes the rifle to short stroke. You just might have to send at least the upper back to BM. I would think after such a long period of time that the gas key being loose would have been obvious. |
I think they'll do you right......they have excellent cust. service, especially on this sort of thing. |
Did you change bolts or bolt carriers? (or both?) (replacing the bolt can check for a gas ring issue). (replacing the bolt carrier checks for a gas key problem). If it still has problems aftwre swapping for a known good bolt AND bolt carrier and you STILL have a problem, then it's most likely a gas port issue. |
I put a brand new BM bolt and carrier in. |
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I got the rifle back from BM yesterday. They said they changed the extractor spring, gas rings and polished the chamber and feed ramp. I never thought it was a bolt associated problem because when I changed bolts it functioned the same. Went to the range this morning and ran every brand of ammo it hated, + some that it liked, and the rifle functioned perfectly. I should have sent it to BM long ago. My hats off to BM for great customer service. |
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