m16 lowers run around 8-10k. then add a 200 stamp and 6 month wait. if you want a beefy lower buy 7075 billet. 7075 aluminum has strength equivalent to mild steel and when machined they are generally thicker in most areas.
the army still runs marksmanship drills in training with m16a2's. marines use a4's for training and in combat. id rather have the 20" barrel. course id rather have an m14 ebr but thats me.
The right to bear arms is WAY less ludicrous than the right to arm bears!