seriously consider the mental health of our youth.

This solution for preventing mass shootings is not stricter gun control. No legislation made by the government is stronger than our God given freewill. Even if productions of all guns were to cease, and all guns seized from each home, if someone really wanted to do a mass killing, they would make their own gun, bomb, or other weapon.
Solution: Create more jobs that work on the mental health of our youth, especially those that display problems in their life that will lead them to jail or worse. Not enough people are educated enough or care to help these problem children before it is too late.
Like no gun is created inherently good or bad, no one is born good or evil. It is the situations that they are given in life, and lack of knowledge of how to deal, that makes good or bad.