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Posted: 7/22/2012 8:22:59 AM EDT
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I recently picked up a LMT 16" upper. I haven't yet bought a new lower for it, so I've been swapping it onto my S&W15 lower.
For some reason, the bolt won't lock open on an empty mag. I've cleaned and lubed it several times, and cleaned the lower. It's a new bolt, lightly used upper (approx 500 rounds), and headspace checked out with go and no-go gauges. I've used Federal M855 and PMC X-tac 55gr ammo only. Mags have been Brownell's, Tapco and the newer Lancer mags (all work fine in the original rifle) Any ideas? If it matters, the original S&W upper still operates fine when I swap it back over. |
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new bolt and BCG, so pretty sure the rings are OK. Plus, it passes the "hold the bolt and the BCG doesn't drop" test.
I have run a .22, but on a CMMG dedicated upper. Also on the same lower. I did clean the lower afterwards, and the original upper is still GTG. The new one is still problematic. I'll check the gas key. I'll wait til I get a dedicated upper before I fool with the buffer, since it's working fine as originally configured. |
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