I take your point about the criminal element Duggan typifies LUHE but the difference in the UK is that society isn't saturated with weapons to the point where anyone with the smallest grievance can start shooting.
I agree with this assessment.
Unfortunately, the level of firearm proliferation of in the U.S. would render any kind of sweeping ban on possession unenforceable. Sales would be easier to enforce. But, as I mentioned, the vast majority of privately owned firearms in the U.S. are not registered. Constitutionally, a police officer would have to have probable cause or a warrant to go into a home and search it for firearms.
Criminals and unstable crazies that have guns would still have their guns after the ban and you wouldn't know about their guns until after they've done something grave with them.