Bought a 10.5" PSA 9mm complete upper with hybrid BCG and a PSA 9mm Glock mag lower and have fired about 1000 rounds through it so far. Flawless EXCEPT for 2 rounds, both which were a double fire on different days about 500 rounds between incidents. The rifle is completely stock as shipped from PSA, other than changing the pistol buffer tube out once I got my form 1 back. Used the original buffer and spring with a new PSA mil-spec 6 position buffer tube when making this change. The double fires occurred once with each configuration.
Not sure if it was a slam fire or something else, but I don't see how it could be a slam fire since the firing pin is not free floating. Any ideas what could be happening? Could this be a trigger issue?
Any and all input is welcome, thanks in advance!