New York state just passed a law that is would define almost any firearm as an assault weapon and goes too far IMHO.
As for me, I would define an assault rifle or pistol as any firearm that is capable of fully automatic fire, any semiautomatic weapon with a more than six round clip, any shotguns with a barrel length shorter than 18" ( already covered under existing guns law), or any pistol with a detachable stock. ( Again already covered by existing gun laws. I might makes a semi automatic rifle exception for some weapons capable of firing a cartridge to larger than a .22LR.
After than we get on a slippery slope with after market parts. Because law abiding buyer X may buy firearm Y, often a variant of the M-16 that fires .223 Ar-15 cartridge, and suddenly use aftermarket parts to make it into far more lethal assault type weapons that should be banned.
As I would also ban the sale or possession of such parts and add a mandatory stiff prison sentence for mere possession, regardless if installed in any weapon or not!
After that and sadly because gun theft is so frequent, gun registration along with a data base of serial numbers will be needed to track stolen guns. That and background checks can greatly reduce but not totally eliminate senseless gun violence without infringing on the right to own and use firearms.
And in closing, one of the many reasons I oppose the NRA, is because, if legitimate firearm owners can't come up and support sensible firearms laws, we will end up with New York State type laws drafted by idiots instead. And when those laws predictably don't work, the idiots will pass even more idiotic laws.
80 years ago the NRA was in the forefront of drafting sensible gun laws, but lately the NRA is the main problem and not any part of any solution, as the NRA has turning into a socially irresponsible lobbying organization.