“Assault weapon” is a politically created term designed to sound like “assault rifle”. Since it’s political construct, it’s definition is subject to whatever a lawmaker proposes it to be - it has no practically useful definition.
The original attempts at “assault weapons” bans would ban the specific models that the law writers found objectionable. The companies could then change the name of the weapon or model number and resume selling it.
So they tried a different approach - what are the common features of weapons we want to ban? Because these weapons functioned similarly or identiically to weapons they didn’t have the political clout to ban, they could only identify them by features like bayonette lugs or threaded barrels. So they attempted to ban any weapon possessing a combination of these traits.
What ended up happening was again the manufacturers just worked around the ban - a weapon couldn’t have a threaded muzzle and a bayonette lug, so they sawed off the lug and didn’t thread the barrel. Result was a nearly identical gun, but legal.
Bans of this type are going to by their nature end up being relatively ineffective because they target things that aren’t part of the core function of the rifle. They can’t be - since these weapons function the same as other weapons they can’t manage to ban, they can’t ban on functional grounds. [edit: I mean ineffective in terms of actually banning the guns they intend to ban, not ineffective in some public good way, which is beyond the scope of a GQ thread.]
Since sometime in the 90s, a requirement was put on that any imported or manufactured weapon that had a counterpart capable of more than 1 round per trigger pull was required to be modified in such a way that you can’t drop in parts to replicate that functionality. Often the part of the receiver where the auto sear would engage is milled out - so you couldn’t convert it even with the required parts.
I agree that the word “banned” may not have the full nuance - but if they prevented the public from buying a certain book, for example, but didn’t make already existing copies illegal, would it be a banned book?