This accepts DPMS barrels, accepts Stag, Armalite and DPMS BCGS and Charging Handles, this assembly can be built using standard DPMS components.
It's an SR-25/Armalite pattern upper receiver with an angled/cut back end, and not the DPMS style rounded corner. It will NOT work on DPMS pattern lowers. The RAIL is a DPMS High profile. Most other AR-10 parts will work (BCG, Charging Handle, barrels/nuts, etc.). To be totally safe, I'd suggest getting a Stag10 upper parts kit. Stag makes good stuff.
Except for the DPMS lower, which will NOT fit because the upper is the SR25 profile. Come on!!