Look, if someone identifies themselves as having a mental illness severe enough to warrant a monthly SS disability check for it, or if their family does so on their behalf, then I say that person doesn't need to be buying guns. I think that's a sane, rational, common sense precaution.
Similarly, if someone has proven so blitheringly incompetent that they have been stripped of the right to handle their own finances, why would they be buying a gun anyway?
The NRA and other gun-rights folks who refuse to support reasonable, logical restrictions like the above cost the Republicans the House in 2018 and might end up costing them the Senate and the White House in 2020.
I'm for concealed-carry. I abjectly oppose all mandatory buy-back schemes. I oppose restrictions on ammo. I think citizens should be able to buy small automatic weapons. Etc., etc., etc. But we are shooting ourselves in the foot by refusing to support very modest, reasonable restrictions on gun ownership, especially when those restrictions won't affect 98% of people who want to buy a gun.