Do you want to build an AR 10 or a .308 AR. An AR 10 is an Armalite, a DPMS is a .308 AR, they aren't the same and the receivers aren't interchangeable. You can buy both types of lowers, an armalite upper is almost impossible to find. Armalite barrels are stamped 7.62 Nato and can't be exported except to LEO's and the military. One shot Tactical just announced he has .308 lowers, although there seems to be some question if they are Armalite or DPMS copies. I built my own Armalite, and picked up an upper from Wolverine, but they are long gone and aren't coming back. If you are going to do a build I would advise you to source everything before you start buying, just so you don't get stuck with a half finished gun. One other thing to think about. You can build a complete car from parts, but it costs 3 times as much. Know what you want and price it both ways. 308 black rifles aren't as common as the .223 ones and it may be cheaper to buy a complete one.