The meme du jour from the NRA is that crazy people kill people, not guns. All we have to do is stop crazy people from having guns, and the problem is solved. How do you stop crazy people from having guns? You find the crazy people. But how do you find the crazy people?
Do gun owners want to submit to psychological screening? Somehow I doubt it; crazy people are meant to be convenient "others". Men in white coats are supposed to take care of them someplace out of sight. They have nothing to do with gun owners. Gun owners will not want gun owners to be the main targets of a witch hunt for crazy people.
So who will be the targets? People who want to buy guns? Will the NRA and the gun manufacturers like the idea of more hurdles for people who want to buy guns? I don't think so.
How about all teenagers in school? Now you have a group people love to test, poke, prod, examine and discuss. A perfect group, with no legal rights to speak of, for a witch hunt.
Mental health screening of all teenagers will turn up all sorts of interesting stuff. It will turn up countless young LGBT kids who live deep in the closet in unsupportive families and communities. It will turn up countless kids who live quietly in horrific domestic abuse. It will turn up countless kids suffering from major depression due to poverty, abuse, minority stress.
It will turn up the underbelly of America. And probably cause a lot of teen suicides.
And then what? There won't be any way to predict which of these countless tortured young Americans will be the next mass shooter, beyond a couple of obvious demographic points: it probably won't be a girl, and it probably won't be a boy who doesn't have easy access to guns.
But what a lovely distraction from the NRA and the gun manufacturers!