Wouldn't work in the US, as was stated repeatedly. Too many guns in circulation. All you'd do is prevent law abiding citizens from defending themselves while giving criminals free reign.
I don't agree with 'the too many guns argument.' (I did once, but that was before I found out how they were distributed). I think the distribution pattern is an important element. There are many gun owners that have multiple guns, so the distribution is not anywhere near uniform. This gives a very misleading picture when one sees only figures for total number of guns in private hands. We will just have to disagree about this.
Also I believe the Canadian firearms registration rules are much better. We will have to disagree about that as well. Most NRA members are very reasonable people in my view, something I am certain you will agree with. It's the NRA leadership that is bonkers.