You might have a point, but it would be a numbers game. Would the potential deterrent effect counterbalance the increased number of gun-totin' cowboys who might be tempted to start shooting in a moment of anger, who might cool off if they first had to go home and get their gun?

Also, using a gun effectively is a skill, it takes some effort and practice, and psychological preparation. I've had formal firearms training and practice frequently at the range. But even though I think I could defend my home from atack, shooting a stranger on the street is something else again. I don't know how I'd react, or if I would engage in combat to protect someone I didn't even know.

Many merchants here in Florida are legally armed, and the bad guys have taken casualties in gun fights, but crime stats don't show any obvious deterrent effect, and there is always the probability that a simple hold up will turn into a shoot first, steal afterwards situation. If the bad guys know you're armed, you become a target because you hold very valuable property they want.

Finally, Florida has a concealed weapons permit law, and anyone who can afford the permit and the safety course (about $300) and pass the background check can legally carry a concealed weapon. But that hasn't stopped the state from having a very high gun crime rate.