Let The Bad Guys Have Their Guns - There Aren't That Many Bad Guys
You know the meme: outlaw guns and only the outlaws will have guns.
That begs the question: what % of the American population qualifies as "the bad guys?"
Well, in 2011, just under 3% of the American population was incarcerated. Perhaps we can assume that the same percentage of "bad guys" are loose in the non-imprisoned population. That would mean that out of 300-million Americans, there are 7-million bad guys in prison and maybe 7-million bad guys not in prison.
There are roughly 800,000 sworn police officers in this country. Just like the bad guys, they have guns.
Ergo, each of those 800,000 police officers would be responsible for keeping EIGHT not-yet-in-prison bad guys under wraps per year in the population.
Considering that even the worst bad guy isn't committing a crime every day (they can't all work on Wall Street, after all!), I'd think that our law enforcement officers could handle the bad guy workload if the bad guys (and the cops) were the only people who had guns.
Bonus: every time a bad guy gets arrested, he loses his gun and maybe goes to jail, and it's not like there's a new bad guy waiting in the wings to take his place.
In the meanwhile, we've taken guns out of the homes of people who aren't really bad guys, but who often end up in domestic quarrels that lead to violence and that - with a gun in the house - lead more easily to murder.