I personally think that you'll see a similar issue with a ban on assault rifles, if that's enacted. If you're already at the stage that you believe you require one for your safety, then you're not going to want to give it up. With their availability at both borders, any outright ban will just increase criminal activity.
The gun genie is already out of the bottle. You'll never get it back in. The only thing you can do is make them essentially obsolete.
If we want to protect children from guns, then we should throw research money at nanotechnology, to create nano swarms on school premises that destroy bullets when fired.
Not to mention the ridiculous military advantage it would give to the country that first invented it...