Here is a philosophical question for youl
I might know an 81 year old gunsmith, who bought a well known M14 action that was and is semi-automatic only. He built an M14 with all military parts and a USGI stock. He might have said, "I can maki it full auto if I want to" Then he might have proceeded to do so with no metal alteration to the receiver, any metal on the rifle, and no alteration to the trigger group.
If a person were to own such an item, What could it become? Could you apply for a Cl. 3 permit and possess it?
Could you sell the secret mfg. process?