California is the best (worst) example of this and probably a model for what our legislature would do with the same power. Currently all magazine fed rifles sold there must have the mag release removed and require a tool to get the mag out. This is known as a "bullet button" gun as the mag release is a recessed button you press with a bullet.
Next year, your CA legal AR will have to be constructed so as to require partial disassembly of the gun to get the mag out. Furthermore mags will be limited to 10 rounds and anything larger must be turned in. We can start a pool as to the compliance rate for this one, and I'm taking 10%. They generously allow any older rifles with the button to be kept, but will be requiring that they all be registered as "assault weapons." I'm thinking compliance isn't going to be real high on that one either.
Scuttlebutt is that next year, legislation will be introduced to outright ban all semiauto rifles.
I'm thinking that by that time Trump will have his SCOTUS judge in place and while getting through the 9th circus is a fairly safe bet, the top court will throw that law out.
Note that only the law-abiding will be required to register their weapons. Felons in possession don't have to as that would violate their 5th amendment right against self incrimination.