I got a midlenth 16" that's got me stumped. It has erratic ejection1:30 to 5:00, & throwing brass lazily only 3 feet or less.. It's has periodic bolt over base malfunctions 2or 3 per mag. After hundreds or rounds through different mags & testing on other carbine lowers & 3 buffers, then tearing down gas system checking for leaks & misaligned gas block which is pinned. I opened gas port it was .063, to.075... test again....to now a huge .093. I know it's over gassed now, but it still ejecting the same erratic ejection 1:30 to 5:00 & only 3 feet.
So today I put it on a standard A2 rifle lower & got a crisp, 3 o'clock ejection pattern throwing brass about 7 feet. BTW the case head looks clean no hard extraction marks, primers are not flattering out or piercing primers.
Why won't it run on a carbine lower with a 4oz T2 buffer or a H1 or standard carbine buffer. It did best with standard before I opened it up but still had weak & erratic ejection and bolt over base ftf.
Im going to try my lower on a friend's midlenth upper, this week. I can't see it being the lower but who knows.
Did I go from under gassed to over gassed with same exact symptoms? Or am I missing something.
My next thing is just try a H3 or 9mm blowback buffer, in my lower.
Any insight will be appreciated, Thank You.
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