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Posted: 5/15/2015 7:00:44 PM EDT
Just completed my first AR upper build and I seem to be having some sort of problem I am hoping you guys can help me out with. Specs are 6.5 Grendel with a midlength AR stoner 18' barrel that came with a properly headspaced bolt. Ammo was hornady 123gr Amax. I put a seekins adjustable gas block on the rifle and have not played with it because I am not sure if I am under or over gassed or perhaps the issue lies somewhere else? Function test with a single round in the magazine seemed fine (with perhaps the exception of slightly scraped up brass? see pics below) Full cycle and lock back with brass kicking out around 2-3:00. However, with a loaded mag it was having ejection issues. The spent round seemed to be getting caught by the bolt as a new round was being chambered. Any suggestions? Thanks in advance!
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Have you tried multiple magazines?
addition: When firing one round from the magazine, the bold would lock back to the rear after the shot. That would prevent it from being able to come forward trapping the round in the ejection port like it's able to do when using a fully loaded mag. I don't have any great advice for you (I'm sure someone will be along who can help you) but, just something that occurred to me. FWIW I'd say try adjusting your gas block. It certainly can't hurt. |
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That brass looks rough as hell. I don't think your chamber was finished properly...or not at all. Could be just the camera flash making it look worse than it really is. Actually I thought the same thing. They all look like that. Something to be concerned about? |
| I agree with Popgunner, chamber looks a little suspect based on the brass pictures. I'd send the pictures you posted here to AR Stoner and their Tech Dept. and see what they have to say. I've seen rough chambers that cause the brass to get stuck and be stripped away from the bolt on ejection acting much like an over gas issue. It could be as simple as brushing out the chamber. Question, are those brass shavings I see by the port door that could have come off the case head ? |
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I agree with Popgunner, chamber looks a little suspect based on the brass pictures. I'd send the pictures you posted here to AR Stoner and their Tech Dept. and see what they have to say. I've seen rough chambers that cause the brass to get stuck and be stripped away from the bolt on ejection acting much like an over gas issue. It could be as simple as brushing out the chamber. Question, are those brass shavings I see by the port door that could have come off the case head ? I'm not sure now looking at the pictures. I think that is deep scratches in the brass from getting jammed up. I bought the barrel from midway listed as an Ar-stoner barrel. Is Ar-stoner the company that makes it? I can't seem to find any contact info. Unfortunately, I have already had the barrel cerakoted so replacing it would be an extra pain in the ass. I polished up the chamber with a cotton cleaning rod attachment and some fltz so we'll see what that does. The jamming problem was fixed by turning the gas down, but this chamber has me a bit worried marking up the brass like that. |
Good to hear you got it tuned to cycle, Some other things to think about, Installing a heavier buffer can help with a over gassed operation and with bolt bounce, Bolt bounce can happen when things cycle too fast, almost like a double tap on the bolt when closing, At one time someone put a video out there that captured the bolt bounce issue. 
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That brass looks rough as hell. I don't think your chamber was finished properly...or not at all. Could be just the camera flash making it look worse than it really is. I have to agree that brass looks like the chamber polishing was never done. I would get hold of the manufacturer. |
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