Already is with the right paper work.
So I can call up FN-USA and buy a new select fire P90? No, I can't. FA is banned except the ones grandfathered in before 86. There is a difference between legal and grandfathered.
I can buy/build new suppressors (Own two, getting a third), SBSs (Going to Form 1 an Ithaca 37), and SBRs (nothing planned.) I can't buy or build a new full-auto. Only pay massively inflated prices for decades old specimens.