I have a few questions regarding building a sbr. What is the process, I know you have to pay a 200$ tax stamp and get the lower engraved. Is it better to set up a trust? My brother got me an early birthday present and gave me cash to go buy a lower and 200$ for the tax stamp. I wasn't really looking to start a new build I might hold off on submitting paperwork is there a time line to actually finish the build before the tax stamp come back? Can I set it up as a pistol if I decide to complete it before I get the paper work back? And can I build 2 uppers for it like .300 blackout and 5.56 or is the paperwork caliber specific.