Possession of both an AR and a full auto fire control group will get you an extended stay at Club Fed, even if it is not installed.You can have the real thing for way less than 35k
FN 15® Military Collector M16 | FN® Firearms
From the maker of the world’s most battle-proven firearms, FN brings you its FN 15® Military Collector M16.fnamerica.com
They prosecute it as ‘constructive possession’.
With a tax stamp and a legal M16 machine gun. I can legally possess spare parts (unlimited?) as long as the parts are segregated in a container marked as spare parts for S/N XYZ ONLY.