One other thing. Not many leo are aware that it is illegal under federal nfa rules for a police officer to take possession of a suspected nfa item. Only a batfe agent may seize such items. Law enforcement when confrinted with an illegal nfa item are supposed to secure the area call the batfe who send an agent who then seizes the device.
The batfe can authorize an officer to secure the item but they cant just take it. Even police are required to follow nfa rules. Police agencies can only posses and use items registered to that agency.
Now, someone can voluntarily transfer an nfa item to a police agency. Once a nfa item is transfered to police ownership it can never be transferred back to civilian hands. This is a dirty trick that agencies in commie states like illinois, california, newyork have used in the past.
Goes something like this... citizen inherits nfa item calls the police to ask what to do, liberal detective says transfer it to us for safekeeping. It gies on police form... ooops that citizen just lost a very expensive nfa item forever.