For the "well, duh" file:
When firearms sales in the Old Dominion rose by 16 percent from 2011 to 2012, gun crime dropped 5 percent, according to the Richmond Times-Dispatch.
That drop in crime includes a 3 percent drop in killings made with handguns, an 11 percent drop in robberies committed with firearms, and a 7 percent drop in robberies involving handguns.
This makes 2012 the fourth year in a row that Virginia saw its gun-crime level drop. Even more dramatically, gun sales rose 101 percent between 2006 and 2012 while gun crime dropped by 28 percent.
This will undoubtedly be a big shock to the people who are perpetually amazed that crime goes down while we keep putting more people in prison. Of course the correlation isn't as strong here. Putting people who have committed crimes in prison cuts down on future crime, but it would be overstating it to say selling more guns reduces gun crime because armed people aren't as likely to become victims.
But we can say for sure that increasing the number of guns does not increase gun crime. It's not about how many guns there are but who has them. Those intent on using guns for mayhem tend to get them illegally to avoid that nasty old trace-the-gun-find-the-criminal police tool. People who buy their guns legally tend to have legal purposes in mind.