Interestingly, Justice Sotomayor concluded the following in her bump stock case dissent. This may come back to haunt the anti-gun folks down the road.

"Semiautomatic weapons are not “machineguns” under the statute. Take, for instance, an AR–15-style semiautomatic assault rifle. To rapidly fire an AR–15, a shooter must rapidly pull the trigger himself. It is “semi” automatic because, although the rifle automatically loads a new cartridge into the chamber after it is fired, it fires only one shot each time the shooter pulls the trigger. See 18 U. S. C. §921(a)(29) (2018 ed., Supp. IV)."