Now my opinion isn't TOO informed, but from what I can see, I think it would be best to have a very gradient policy on gun ownership. For example, you can't walk around with a rifle in your jacket, but you can conceal a pistol in your back pocket. This is because a pistol offers one the maximum amount of personal safety, while also being something on small enough of a scale to make it relatively secure for everyone else in the area. You also, of course, need a license to do this, which is a good idea.
Therefore, it should be legal for someone to keep rifles in their car, because your car is a slightly more private place. You shouldn't be allowed to wave it around the back of your trunk in the middle of a busy parking lot; it's only there as protection for the possible threats and dangers that could follow you on the road or wherever you may go. Again, like before, this grants you the most personal safety without also shoving the danger of the weaponry in the face of others. And you also should need a license for it.
You should be able to have fully-automatic machine guns... in your house. Because houses are subject to organized, planned burglaries by potentially multiple bad guys at once. But more importantly, the privacy of a house means there's a much wider range of privacy. It should be required that a fully automatic weapon be locked securely away when not in use; it should be required that you can't take it out to start playing with it unless you have enough land, and if you live in a tiny apartment with tons of other people, security should be the responsibility of the owner of the apartment. And again, you should have to get a separate license for these kinds of military-grade weapons.
What about tanks and turrets and rocket launchers? Well, you should be allowed to have all of those... if you basically own your own private city. Yeah, like, if you somehow have thousands of acres of land and multiple buildings and it's basically a little town unto itself with hundreds of people working and living there, then your property spans such a wide radius of privacy, that it could comfortably fit military-level security. After all, if people owned cities (which no one in America does; I'm just being hypothetical because this is a hypothetical thread), they not only COULD safely operate such weaponry, but would probably NEED it.
Getting the licensing for all this should be a massive deal; it should take countless inspections and regular oversight by government agents.
So there's my gradient approach to how I think maybe gun laws should be.