Ordered a 8.5" 300 blackout upper with the intention of filing for tax stamp to make my setup legal. Once lower is engraved can I also run a 16" 300 blackout upper on it as well?! Or maybe even a 8.5" 5.56 upper later or is this "upper" specific?
Any help would be great! Thx!
Any help would be great! Thx!