Colorado, where the recent gun massacre occurred, has one of the loosest gun regulations in the country: there are no limits on assault weapon ownership, no limits on handgun purchases per month, and no permits or licenses required for gun ownership. The state has no authority to regulate guns, while safety measures such as safety lock requirements are nonexistent.
With all that said, most research I’ve read suggests that gun policies, whether strict or loose, have little to no effect on gun violence. Instead, the underlying causes are child poverty, a lack of mental health services, socioeconomic inequality, and a lack of community cohesion. It’s much easier to change a law than to change society, hence why most people seem to defer to the former option as a solution.
Granted, if anyone has any data that show the opposite conclusion, please feel free to share it. I’m just going on what I’ve read and studied myself.