I'm finishing up my build and have a problem with the bolt carrier.it wants to hang open most of the time.a slight tap or bump and it closes.it appears that when the bolt is directly over the hammer,the spring tension of the hammer is pushing upwards on the bolt carrier.the groove in the bolt carrier that the top rail rides in on the left side raises up just enough to bind right where the top rail is notched for the bolt carrier to be dropped in.could I bevel the leading edge of the groove in the bolt carrier or????? thanks