Felons & the feeble minded.
This short list could be added to, but those immediately came to mind.
Sometimes, gun ownership is prohibited if someone files a PPO against the owner.
This shouldn't be automatic, but could be a basis, depending upon circumstances.
With all respect, you could be a wrong person to own a gun...
Things never go well when a sentence starts out with "With all respect....".
Just kidding!
But such a judgement wouldn't be made using only internet posts.
When I got my CCW license back in the 80s, I was evaluated by
a board assembled for that purpose. It's doable.
Just pointing out the subjectiveness here.
It can be made quite objective.
But given our long dialog on the matter, I do respect you as a responsible gun owner. I know there are other responsible gun owners out there besides you.
Flattery will get you everywhere!
Almost everyone sees themselves as the right moral person to own a gun. That's because the 2nd amendment doesn't limit ownership and has been used to justify ownership almost as an innate right of humans. That is the culture being defined in the US and it all starts with the 2nd amendment.
I'm OK with assessment being made according to objective standards.
I think responsible owners should still be able to own guns but they have to prove it. Other nations like Korea and Japan have very strict policies on owning guns. Ownership should not be a right.
But since ownership is a right, & one not likely to go away any time soon, I
prefer addressing legally possible methods of reducing gun (& other violence).
It should be a responsibility through extensive training and extensive evaluations. The argument of a bad guy can bypass this to own a gun is true but real-world statistics prove that this goes down as the number of guns go down. This argument is still true for other restrictive nations, it's just much more difficult for these bad buys to obtain these guns so the percentage is less. Again, statistics prove this.
I favor more training. I see benefit in it.
But I admit bias because I had much more than most.
On a tangent, I think ownership should be divided into purpose like hunting, sportsmanship, self-defense and so on... Each purpose has different restrictions on the gun type and how/where its stored. And there should be a division specifically to address the intent of the 2nd amendment. There should be organized militias, however, these militias own the guns and are responsible for their safe-keeping and operations.
There should certainly be different kinds of training for hunting v self defense.
Btw, I favor more training for anything potentially dangerous, eg, driving on roads.