I bought an AR10 Armalite lower a few years back and then all the stuff that ran up gun prices happened. I waited to see if prices would come down and they seem to be now. I need to build or buy an Armalite upper. I see Stag has them upper with BCG for 389 and would still need barrel, barrel nut, gas tube, hand guards. not sure what else I would need. Thanks for any help. I do have the Armalite not the DPMS lower.