I think one issue with all of this talk is this:
This stuff doesn't just happen at schools. Vegas, churches, malls, etc. Mass shootings in general are a huge issue in the US, not just at schools.
What is the root cause of all this? Mental health. None of these cats shooting places up are right in the head. Ban guns? They drive through crowded areas in a Home Depot van (yes I know that was more religious based).
Here is my point:
I personally am on depression medication. I go on it for 3-4 months a year during the winter. I have NEVER had an issue with my background check and I own multiple guns. I get approved the same day, no issues, etc. Why? I've always questioned that. Why is it that someone who is on depression medication and has a history of mental health stemming back to 2012, is able to get a gun so easily?
PS: for the record, I take the lowest dosage of anxiety/depression medication known to man, usually from Dec-March because of the lack of sun. I don't have actual depression, just seasonal. But my point remains- it's never once come up on a background check.