I have a Bushmaster XM15-E2S and for the last year and half it has worked like a charm.  In the last 2 months I have noticed about every 100 rounds the bolt carrier key screws loosen up so much the rifle stops loading the next round.  I disassemble and tighten and then it works perfectly for another 100 rounds or so.  I am hesitant to put something like locktight on and am thinking about just trying some teflon tape.  I saw a previous post where someone suggested just ordering new screws --- will that solve the root issue?? Anyone have any experience or suggestions.

Thanks

Torque to the spec. (38 to 40 inch/lbs.  I think--double check it) and then stake them.

Thanks for the quick reply.  Tweak that post with the pix will help alot.