They could do like with college loans or leases and have a cosigner for getting a gun and if the person who gets the gum gets in any trouble with it some of it falls on the other person. Okay that's kinda crazy I know but it could inhibit bad things because the other person would be like oh snap they're acting sketch let me report them before I get in trouble.
But there are a million ways that could go wrong. Or not change anything at all. The cosigner could steal their gun but that wouldn't change anything that happens now anyway. Or there'd be less guns BC no one would sign for anyone cause everyone crazy anyway and ya can't trust no one.
That's what I would do in my world but in my world we wouldn't have guns we'd have wands and the ministry *cough* I mean government would know once your wand did an illegal curse.