I have decided to take the plunge and buy an ar-15. I'm stuck between getting an armalite, or a dpms. I've heard that dpms rifles will not except other comapnies part? Is this true? Also How do these to brand compare as far as quality goes? I don't mind paying the extra for the armalite if it is a better gun. Secondly what are my options for optics? I would like something that will work for distance and something that is fast mounting. My budget for the scope is about $400.