The jack-booted ATF thugs claimed their scalp... an Army vet.
Full auto, defaced SN, no BATF paperwork. NOT a good idea. Long after NFA ‘34(?).
An Army vet (and there are lots of them, of all kinds, some not at all good citizens) who was not willing to obey the existing law and obtain a Class 3 Federal Firearms License that covers automatic firearms, and refuse to own or keep a firearm with obliterated serial number. Seven years is not a bad sentence for a deliberate law-breaker.