Curtailing access to them means that some people cannot get them. That may be a problem...
People talk about keeping guns out of the hands of the mentally ill. Great in theory, but is MUCH more problematic in practice. Mental illness is not binary -- it comes in various degrees and kinds.
Should a person who hears voices telling him to kill people be denied a gun? Probably.
Should a person who compulsively washes his hands be denied a gun? Probably not.
If a person is on anti-depressants be denied a gun? What if they stopped taking them (this could be good or bad)? What if they stopped taking them last week against their doctor's orders? What if they stopped taking them 20 years ago?
Suppose a person is dangerous enough to require having their rights to arms removed... Who makes that determination? Does it just take one psychologist? Should it take a board of 3 or 7 doctors? Should a judge be involved?
If the person gets better, how are their rights restored? Once again, who makes this determination? What are the criteria?
And suppose a person already HAS guns. Maybe they are a hunter, and love hunting. Because they are afraid of loosing their favorite recreation, they AVOID seeking mental help. Is that a great idea?
Suppose a woman has some mental health issues and is denied a gun. However, her ex has a criminal record for violent offenses and has threatened death against the woman. Should the then be allowed to own a gun to protect herself? If so, who makes this decision? How long would it take for this issue to go through the courts? Would she even live that long?
Seriously. just focusing on the guns is ignorant. Just saying "don't give them to lunatics" is easy to say, but much harder to do in practice. When there IS a school shooting, what is the first thing to happen? People show up to help, with guns.