“Any argument about automatic weapons should focus on the laws that ban them”
They’re not banned.
Correct. My late brother legally owned three (or more) of them, machine gun's, along with a few noise suppressors (aka silencers). Regulated but not illegal. He was a firearms collector or rather a connoisseur of finely made and sometimes rare firearms and was a trader who was properly licensed. I always loved perusing his large collection of them and going to the range with him.
They are in some states. In any case, laws which have resulted in the market price of an M16 being $20,000 or more are a practical ban.
Just as when gun grabbers argue that they don’t want to ban ammunition, they just want to tax it at $100 per round.