So I took my new pistol build out to the range this weekend and was having an odd malfunction that I’m having trouble diagnosing. With each shot, the bolt would lock to the rear—even with rounds still in the mag. All the parts are new, and after a few mags, the issue seemed to go away. I ran some more ammo though it, then on my last mag of the range trip, the bolt locked back again in the middle of the mag. I tried two different mags – a pmag and a lancer – and seemed to have trouble with both. Although the lancer had far fewer ‘lock backs’ than the pmag did.
Half of the shots were suppress and half weren’t. Seemed to have more issues when shooting UNsupressed. I’ve played with the mag catch and the spring/catch/detent and all seem to be within spec and operating normally. Thoughts on what could be going on? I plan to go back to the range this weekend and swap out with different uppers/lowers to see if I can isolate the problem.
Specs:
Lower
Noveske stripped lower
Factory colt LPK
Giessele trigger
KAC ambi mag release and safety
Maxim Defense PDW brace with JP silent captured spring (Heavy)
Upper
Factory complete BCM 8” 300blk upper
Factory BCM bcg
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