I'm glad we largely agree. Still, I have a few points:

But none of it is legally feasible, for all the reasons I have already stated, and more.

I might be completely missing some basic understanding of your legal system, but isn't the Consitution a living document, at least to some degree? What are amendments if not improvements over that supposedly enshrined set of rules? (And wasn't it Jefferson who said the Constitution should expire after 19 years?)

In a fascinating question-and-answer event in 2005 between Supreme Court justices Antonin Scalia and Stephen Breyer, the question was broached as to when and how the concept of a "living" Constitution came to be. Scalia opined that the Court first began employing relativism to a significant degree starting around 1945, right after World War II. As Scalia says:

"[T]he Court adopted the notion that the Constitution is not static. It doesn't mean what the people voted for when it was ratified. Rather, it changes from era to era to comport with – and this is a quote from our cases, "the evolving standards of decency that mark the progress of a maturing society." [...] It seems to me that the purpose of the Bill of Rights was to prevent change, not to foster change and have it written into a Constitution."

This seems to me a clear example of society maturing, becoming more civilized.

We are NEVER gonna be able to reclaim any significant portion of the 250+m guns in private hands in the US.

Yet you give some good suggestions for how to do that in the top post! Maybe I'm just more optimistic and / or naive than you in this regard, but I think that a restriction on ammo and a reduction of supply might help quite a bit.

Remove the guns, and you still have angry white men with ANFO.

And less suicide! Over here, women attempt suicide more often than men, but men succeed more often because they use more drastic (and less fail-prone) ways of suicide, like jumping off a building instead of trying to ODing on over the counter medication. I distinctly remember a factoid that the most dangerous single thing you can do in your home (largest increase in likelihood of death) is to get a gun, as it might make a difficult night into your final night. Can't find the source, but my point is that the availability of guns is not an insignificant contributor to the problem, and that I think "just" calling it a societal problem is a reduction of the complexity of this problem.