I have BCM pistol lower I acquired secondhand a good while back that I had coated and rebuilt. It had an aftermarket trigger installed with KNS pins that I replaced with a BCM PNT trigger I had in another rifle. I can't get anymore than 2-3 shots off before the pins start drifting out and the gun won't fire. The trigger was fully functional in the other rifle and I have reinstalled the trigger several times to try and eliminate possible installation error with no improvement. Any recommendations on what to check into next or am I stuck using one of those crummy cartridge-style triggers with anti-walk pins?