heres a little something i did today at work a non-nfa xm-607 moderator. its 3.3" long 1" .750 recess. 5/8 flats. i put a band of tig weld to simulate 2 pieces. its heavy at 9.4 oz. thats cause i left thehole at .297 all the way through so it will look like a moderator from the front.