OK, my brother is looking into building an AR vs. buying 1. I have been watching the classifieds and seen a few that I like, but not necessarily what he likes. I am a Glock guy and don't know much about ARs to really help him. Is there a guide on here that will help me out? No luck using the search feature. And who has a list of links on where to look and get parts? Seems like AR parts are like Chevy parts. Everyone has 'em.