"Aren't you concerned that this makes it easier for criminals who want to steal firearms to use in violent crime to know which houses to watch?"
I agree that burglars have a penchant for stealing firearms. However, they don't need a map to do so. A 2003 study from the Brookings Institution found "no support for a net deterrent effect from widespread gun ownership," and concluded that, "residential burglary rates tend to increase with community gun prevalence, while the [occupied dwelling] proportion of these burglaries is unaffected."
Does this make it easier for a criminal to find a home with a handgun permit? Yes it does. However, the map's information doesn't specify whether a gun is at the residence in question, how many weapons might be there, or what its condition is. The map is far more useful to parents who might want to understand what risks their children may face at a friend's home.
As a potential parent, I would not want my child to play in an environment where a gun is present until I was assured that the firearm was secured in a manner that prevented an accidental discharge. I don't want to claim that the map in question is a journalistic breakthrough, but I would appreciate it as a tool to understand my safety and the safety of my loved ones.
Firearms at home are more likely to wound or kill their owner (accident or suicide), the owner's family members (domestic violence, homicide accident, suicide), or a person known to the owner (dispute, accident, homicide) than an intruder--besides, even trained professionals (like the armed police officer at Columbine High School) can make mistakes in a crisis, let alone a sleep-addled civilian without rigorous training and regular practice. Ideally, firearms at home are locked within gun safes, which would present burglars with a challenge and/or fitted with a trigger lock to reduce the risk of an accidental discharge.
Indeed, higher firearm ownership, and shall-carry laws in particular, does not reduce crime in a way that is statistically significant. To the contrary, it is more likely that increased firearms in a community will increase crime or behave heterogeneously, depending upon local and county characteristics.
I'd be interested to learn what articles have shaped your thinking on firearms, their role in our society, and how to move forward in the wake of the mass killings in Connecticut, Colorado, and Arizona of recent years.
Here's my top reading list on this issue:
1. Nick Kristof offers hard statistics and a public-health approach
2. The deleterious effect of an armed populace on civic society
3. Gail Collins examines the politics of guns with a biting sense of humor
4. Nick Kristof responds to reader comments from gun enthusiasts
5. Something way out of the mainstream--interesting but not politically practical