I have a flattop M-4 type Bushmaster with an Aimpoint.  It all works well until I shoot 50 or so rounds and the mount gets loose from the rail.  It has a thumbnut that, when it reaches a given tightness, flips over and it can't be tightnen further.  So I need to either get a good mount that will stay put or figure out a way to adapt the one I have.  Is there a good  mount that is solid as a rock and still allow me to use the iron sights through it?  I haven't seen this problem discussed here before.  Sorry if this is a dupe.  Any ideas?

sounds like the nut is stripped.


larue tactical
a.r.m.s
troy
gg&g

all offer good mount for the aimpoint and the taller or cantlever ones co-witness with you irons. i personally perfer the larue tactical cantilever mount.