I have a brand new, never built mayhem machine and tool m16 slick side upper, and a very lightly used aero precision 308 / ar10 bolt carrier group. Willing to sell or trade. I need a 556 bolt carrier group (name brand please, I'm not interested in no name bcg) and a minimum 16 inch 556 barrel. Open to other trade offers. Text is best at 817-793-four eight five eight. Located in South Arlington