I just built a Aero Precision M5 pistol. Everything is Aero Precision except for the SLR adjustable gas block, SBA3 brace, and AR15 JP Silent Captured Spring. I’ve put about 150 rounds through it and every time the BCG will not lock back. Even just putting an empty mag in it will lock back but any little movement will cause it to go back into battery. I’ve tried all the different JP springs, I tried switching the buffer combo to an Aero Precision M5 Pistol buffer kit and it will still not lock back. Any thoughts? Thanks for the help.