Wrong guy, my frenetic, projecting friend; I've discussed them ad nauseum.
Sanity check #1: there are likely about 350 millions guns in circulation. What makes them good for defense makes them good for offense/crime. That vast pool of guns ensures anyone who wants one, will. The Bureau of Justice has found that nearly 1/2 of gun felons used straw purchases (someone who can buy legally is actually illegally buying for another person); those are entirely unstoppable, all you can do is prosecute after the fact AFTER the gun turns up in crime or felon possession. "But universal background check!"....yawn!...well, okay if I want to give a gun to my crazy sister I guess she should undergo the same check as anyone else buying a gun. Checks that are so ineffective now, that your insisting we merely expand them to these private transactions. Which criminal straw buyers, for example are already violating. So yes, let's fry all the little fish while ignoring the shark problem. Is this microphone on?
Anyone who is determined to shoot up a school likely can do so if schools are not hardened. It's not settled that even a majority of mass shooters are mentally-ill even if some spectacular examples of shooters were. The most lethal shooter in U.S. history, Stephen Paddock - the Vegas shooter - had no diagnosed illness and was a successful businessman. You will never identify people like this before they act.
"Okay! - people who are diagnosed then!" So anyone from those experiencing anxiety , non-violent benign phobias, or insecurity all the way to the schizophrenic - 50 million adults - are to be denied their right without due process? Tell me how this is supposed to work, even if it weren't such a fked horrible idea, when HIPAA laws & patient privacy are vigorously defended by "transparent gun lobby shills" (your words) like the ACLU and conscientious, constitutionally centered people on both sides - ?
Are you beginning to see the problem? With vapid comments like "killers will just wait outside" while accusing others of mental avoidance gyrations, I doubt it. No kidding Sherlock; hermetically seal your child away from the world if that is your primary concern, because a malevolent person can kill them ANYwhere. Will you protect your child as best you can and have them live in the world, or seal them away?
I'll frame it another way before you go. One thing and one thing only stops mass shooters; being shot by someone else. That's it. When all your fetish, prevention measures fail - and they always will - someone had better be prepared to defend your child with a gun. And in the moment they do, you won't give a shite whether they're police, armed guard, or a teacher who swore he/she would not stand by and took training to prepare for it. You'll simply thank the heavens they were there and didn't subscribe to your fetishes. A serious, caring person who took responsibility and action.