I ain’t bringing logic into it, I’m just pointing out how the law has been interpreted.

Attaching things to guns that enable fully automatic fire as it is defined by the law, i.e. more than one shot per activation of the trigger, do count, though. This includes things such as full auto sear or those fucking “Glock switches” that are so popular these days.

With a crank trigger you have to keep cranking it to keep firing, like an old wild west Gatling gun. You can’t just hold it down and the gun dumps the magazine on its own. A bump stock aids the user in rapidly pressing the trigger over and over again. You can bump fire a rifle even without a bump stock if you are sufficiently practiced or skilled.