I think you need to split this question into two parts:
- what do you do about sales of new guns?
- what do you do about the guns that are already at large?
So I think if you want to push the legislators into taking action, then you need to limit the amount of pressure that can be exerted by groups such as the NRA. And, of course, you can't just pick on the NRA - if you bring in new rules they have to be applied to all pressure groups. Politicians need to know that if they were to take an anti-gun stance, that their re-election pot won't just evaporate. But right now, it's not even clear that America wants gun control. We hear a lot about it in our [UK] media, but the UK knows only too well about extremely vocal minorities, and it's not unkeard of to hear of media companies pandering to the whim of their audience.
But for that reason, I think you're looking at the bigger issue of political funding. I haven't really thought about how you'd do this, I don't much have a preference, but the aim would be to have politicians unable to be bribed by pressure groups.
This, in turn, would take the NRA out of the equation, as an excuse for why gun legislation doesn't happen. I mean, it could well be that America does want guns, but at least then the politicians have a free hand to reflect the views of their constituents.
To the second question, I'm afraid I see no solution. I have heard it said that some people carry arms so as to defend themselves from excessive behaviour by the state, I think that this was the rationale behind the Second Amendment in the first place. Even putting the legitimacy of this belief to one side, I think it is fair to say that you're not going to persuade these people to give up their weapons. So I'd predict bloodshed.
Who knows? Maybe the argument comes full-circle and that's why politicians don't take action? Although I've never heard that view expressed.
I really think that, on that point, the genie is out of the bottle and there's no going back. I despair for the USA.