I disagree. Gun control can be effectively instituted in the US, but it would take a few generations. The NFA was surprisingly effective... All they had to do was grandfather the current ones if they are registered and make possession of an unregistered one illegal. From there, make transfer illegal and bam! Sure, you might get to keep the AR you have until you die, but your son or grandson will likely not be willing to risk the felony charge for trying to keep your AR after you pass.

(Unironically: Reeeee, no step.)