They don't know, and generally care less
Back in 1994, the country fell victim to an effective disinformation campaign about "assault weapons". Gun banning politicians got the "assault weapons bill" passed on a federal level, albeit with a sunset provision 10 years down the road. Several states passed very similar bills, without the sunset provisions.
Generally, these bills banned ownership of new made (or imported) semi auto guns with certain cosmetic features. And that was it. No new magazines over 10rnds, no guns with such "evil" features as flash suppressors, bayonet lugs, pistol grips detatchable magazines, etc. 2 or more of these features was sometimes enough to get your gun on the banned list. And many models of guns were specifically banned by name.
Guns and magazines already owned in private hands were "grandfathered", meaning they could continue to be owned, and sold. Some states required their registration.
The whole thing was about what the guns looked like, not how they worked, or what calibers they were in.
Sarah Brady, and various politicians even admitted that the law really had no effect on crime, but they considered it a "necessary first step".
The real truth is that, to politicians, gun control isn't about guns, it is about control!