I bought a DS4 kit from J&T Distributing, which had a pre-assembled upper included. That was the first and only AR I've built, and it took me less than an hour and a half. I worked pretty slow and read how to's on several different forums to check and doublecheck that I was doing it right.Machinisttx, just curious but, did you buy a "kit" for your AR builds or just source all the parts yourself? I've been wanting to build an AR for awhile, though I still have a few months before I can afford to build what I want (I'm really wanting to do an AR10). If you have any advice, I'd love to hear it.