Gunfighter1775

I have a Stag Arms Stag 10 lower receiver. I know that it is not compatible with DPMS upper receivers because of the fact that it is modeled after the Armalite lower receiver. I am wanting to do a 10.5" build (I know stupid and crazy), but I want to know that my options are for barrels and hand guards with it also having a Stag 10 upper. I'm lost please help!!!