Forgot to mention there's one small issue when using FM lower with Taccom. There is a small "hook" on the lower that activates their bolt hold open. It touches a corner of the feed ramp on Taccom barrel. Easy fix is to take dremel and cut off hook. I don't use BHO, so it wasn't an issue for me. Other option is to relieve corner of feed ramp. If you're not comfortable with these, any quality lower will do. Possibly QC10? Also highly recommend hiperfire trigger and Holosun optic.