Beside having a Gun Control owners should also be more calm and ensure that their mood won't affect on thwir decision when using it.
There is no way to ensure this. A person who seems calm and peaceful today may be the one who kills a few dozen tomorrow in a terrorist attack. Mood depends on a lot of things.
So the only viable method is to remove guns from the criminals, and the mentally deranged, and allow gun ownership for everyone else.