I agree in principle, but not in practice. In principle, you could also say the primary problem was private access to firearms in any way was the root problem. In practice, hundreds of millions of guns are kept safely and responsibly. The problem is that some unregulated persons are able to freely buy mass murder in a box at the local store. Dealing with this very small subset is the problem, and IMO a manageable one that does not push hard against the responsible sportsmen.
Again, respectfully disagreed. Millions of sportsmen manage to not go postal. Millions. Many of these people live in rural areas where formal ranges are financially impractical (you won't have a lot of thousand yard ranges in a poor area. They get expensive). The problem as I see it is a guy like Cruz getting his hands on modified military weapons. They have no business in the hands of a non-combatant. How much you can store at home becomes an academic problem; the black market is alive and well, as is illegal storage. The issue is clearing the weapons and ammo off the shelves and regulating the gray market. If these guns are not readily available to guys like Cruz, the threat is effectively minimized.
I think home ownership is closer to 5% of the problem. 95% is access to weapons which have no business in civilian hands. Consider the UK (as I have been reading about). Shotguns and small caliber rifles in homes, with ammo, and no daily mass shootings. Seems awfully effective to me.
I think we are largely in agreement, except for defining the hilited. You seem to think any gun is a lethal weapon. That's true, in the sense that a baseball bat is, too. I think that rapid fire high-capacity guns are the enemy, not a hunting shotgun that holds 1-3 shells. Adopting the NJ laws, with a little tighter regulation, seems tolerable to both sides of the debate. New Jerseans are not exactly a docile bunch, and we manage to get by. The rest of the country should be able to cope with reloading a little more often for the sake of putting the brakes on mass murderers.