I leave only the rear REAR of the recoil lug untaped; I tape the sides, the front and the bottom of lug. The lug is there for one reason only, and that's to be the primary receptor of longitudinal forces (recoil) - the bottom areas of the receiver in the vicinity of the front and rear rings are the areas that provide the main support and directly opposite of the forces applied when tightening the guard screws. By leaving the bottom of the lug 'floated', I don't have to worry that the lug can in anyway become a third, possible pivot point.
