The 1986 Assault Weapons Ban in the US restricted the sale and ownership of several non-existant gun attachments and modifications. It also for some reason banned specific guns like the KS-23 (quite ridiculous gun you should read on if you're a fan of them) that was only manufactured in the Soviet Union and other bloc states and literally couldn't be imported to the US normally regardless because it used the barrel off a 23mm aircraft cannon.

Remember to always put someone with no knowledge of guns in charge with making gun laws.