Ideas someone gave me for fun 21st Century determination letters to ATF:
A bionic arm that’s capable of pulling a trigger at automatic speeds based on nerve inputs, but in an entirely controllable and accurate way. Machine gun?
My take: no. The bionic “finger” is still actuating the trigger each time. But what if the arm enhances the biological capability to allow the finger to work very rapidly? What if the user firmware hacked his bionic arm to do very fast finger actuations upon certain nerve impulses? Can a bionic arm ever be a machine gun? The answer might be “probably!”
A firearm is produced for disabled shooters with no trigger. It’s firing mechanism is actuated by thoughts. However, someone figures out it’s capable of firing continuously if the user thinks about it in a certain way (Maybe you have to think in Russian!), but the firearm has no trigger as we understand the term today. Machine gun?
Presumably there could be a mechanism that could be identified as a trigger. But what if it is otherwise an ordinary semi-automatic action that’s electrically actuated and it’s the right kind of thought that actuates the sear either singly or continuously. This is a tough one. ATF has traditionally not wanted to get into rules of “if you use it this way, then no, but if you use it this way, then yes.” I would argue our law does not describe this kind of situation, and absent action from Congress, not a machine gun.