wally
Member
This might be better in the Gunsmithing and Repairs forum but I suspect most of the SBR expertise is here.
I've an M&A Parts 11.5" 7.62x39 AR upper and it appears to be short stroking badly. Suppressed it seems to run fine, ran a mag and a half this morning after trying everything I could think of unsuppressed. I've tried standard, H, H2, and 9mm buffers, a couple of different recoil springs and nothing seems to let it lock the slide back when single loading one round in the mag. Suppressed it always locks back. With two in the mag it fails to strip the last round, sometimes the empty ejects, other times not. Single rounds always eject, but weakly.
I even swapped in the MGI bolt & carrier from my 16" 7.62x39 carbine upper and it made no difference either
I see no evidence of any gas leaking around the FSB.
I assume the next step is to open up the gas port in the barrel. My question is what should the port diameter be on an 11.5" 7.62x39 AR?
Any other potential solutions I've possibly over looked?
Accuracy seems very good and the POA/POI shift suppressed vs. un-suppressed is pretty negligible at 50 yards using a red dot optic shooting off sandbags.
My main motivation is to run it suppressed, but I'd feel a lot better with working un-suppressed, as I doubt it'll handle much fouling the way it is now.
I've an M&A Parts 11.5" 7.62x39 AR upper and it appears to be short stroking badly. Suppressed it seems to run fine, ran a mag and a half this morning after trying everything I could think of unsuppressed. I've tried standard, H, H2, and 9mm buffers, a couple of different recoil springs and nothing seems to let it lock the slide back when single loading one round in the mag. Suppressed it always locks back. With two in the mag it fails to strip the last round, sometimes the empty ejects, other times not. Single rounds always eject, but weakly.
I even swapped in the MGI bolt & carrier from my 16" 7.62x39 carbine upper and it made no difference either
I see no evidence of any gas leaking around the FSB.
I assume the next step is to open up the gas port in the barrel. My question is what should the port diameter be on an 11.5" 7.62x39 AR?
Any other potential solutions I've possibly over looked?
Accuracy seems very good and the POA/POI shift suppressed vs. un-suppressed is pretty negligible at 50 yards using a red dot optic shooting off sandbags.
My main motivation is to run it suppressed, but I'd feel a lot better with working un-suppressed, as I doubt it'll handle much fouling the way it is now.