07-08-2020, 04:57 PM
In my recent upper build, I wrapped a cut piece of heavy duty aluminum foil (a bit under .001) and mounted. It ended up getting it to go in without any big hassles and it was a pretty tight fit without needing to use any Loctite. I do not see a point in lapping the receiver and was not possible on the Aero m4A1 enhanced upper I used on the build.

