This muzzle protector is an improvement over the original bringing the length of the barrel from the muzzle to the trunnion/receiver to 420.471mm which is 16.554 inches so it isn't a sbr. Use lock nuts on the 1/4 in threaded rods to hold in place.
LBRY Tags: fosscad; 3d2a; guns; 3d printing; art
NAG funnel and drill jig
Bastard son inside barrel install jig v2
AR15 flash hider pencil holder