You are right but this goes beyond the mental ill. Even if this happen in front of them, these hardliner won't change much. They'll simply make excuses. It's the culture that we live in. 57 dead and 500+ wounded, did anyone with a gun besides the officer kill him? No, he committed suicide. Never thought one person can take down that much people. Guess bullets can double hit or ricochet. The simplest solution is to remove the guns. The effect won't be known in the short run but definitely in the long run. But no, not in America.
Illegal guns are the larger problem. You might get a couple of these events per year. So you need to penalize hundreds of millions of people that mind their business? Terrorism were told is not all Muslims, so how about not all gun owners are responsible for mass shootings?
You people are so ready to sign over rights and allowing the government more authority...
In the end, you can't regulate evil. The blindness to that is staggering. Anyone can go rent a truck and drive it into the crowd and kill this many people, or more.