The other 1st-world countries do not trust their citizens to be armed to the teeth, and it works. Basically, the more guns per capita, the more homicides per capita (see rationalpatriotismfoundation.com/index.php/what-the-newtown-gun-disaster-really-tells-us-guns-are-the-problem for the graphics and statistical correlation). The Brits, for example, are a pretty violent lot. Young males like getting drunk at the pub and at football matches and having at each other. But they cannot get a hold of firearms they being rare in the nation, so the death rate is very low. No country with lots of guns has a low homicide rate, no 1st-world country with few guns has a high level of murder. It's not rocket science, it is intelligent policy based on an understanding of the frailty of the human condition.
So do not, repeat do not, trust the gun owner. When someone tells you that they own guns and would never do wrong with them, feel free to tell them you do not trust them to never kill. And why no one should trust anyone, or themselves. If you do not feel free to do so because you suspect that might tick them off and who knows what they might do -- well that just confirms the point. Dating someone with a gun? Reconsider. Seriously. Why deal with the potential threat? It's as smart as dating someone who smokes. Got guns in the house? If you want to minimize your chances of premature death, get rid of them (or at least of ammo -- have the shootist purchase that on a need-to-use basis). If you don't, you are gambling with your life and with those of those you love, or at least live with.