Okay youse gize that build your own. What parts would you use to build your own AR-15 to these specs: Flat top with flip up BUIS M-4 copy Capable of head shots at 200 meters every shot. As near as humanly possible to absolute reliability Chromed barrel and chamber Direct gas system. Second question: After it was built, would it be any less expensive, or better quality than a factory Colt. I've never built one, but it seems like an interesting project if the results will actually give me something better. Thanks in advance for any and all advice.