Considering we have one of the largest number of guns per capita in the world, our crime numbers are low, crooks think twice in Miami before breaking into a home, as 95% of homeowners are armed. Miami's past crime rap was due to cocaine cowboys and a rash of carjackings in a bad part of town that unfortunately has an airport exit that confused tourists, and landed them in the middle of Liberty City, not a nice place to be. Most gun crimes are not committed by law-abiding citizens, but a select few that will still have access to the weapons even if banned. If you expect the courts and police to protect you, good luck. The scum will always try and prey on the weaker, the gun is the great equalizer.
As for the US having an inordinate amount of "loonies," well you can argue that armed illegal political factions, terrorist groups, para-military gangs, killing hundreds of thousands around the world make our thugs look like girl scouts, they're no different than our criminals, they're illegal, breaking laws and murdering people, that they're quasi organized makes no difference, remember the mafia? So in the big picture we're still pretty civilized when compared to other parts of the world. I won't travel to South America, Jamaica or Mexico they are worse than the US in per capita crimes, Brazil is a virtual war zone. It's when it happens here, it puts us in a bad light and you know how the world feels about the US.