[AnimalMuppet]

Well, as actasabuffoon pointed out in a parallel post, there is an argument to be made that this wouldn't work very well in the modern setting. But yes, if we're going to change it, we need to amend the Constitution.

For example, the amendment could say that "militia" means the National Guard, and that is in fact supposed to be a significant fighting force, with military-grade weapons and people trained and ready to use them. And for personal use, people can have weapons sufficient for self-defense but not for mass murder.

But for that to happen, we've got to persuade 3/4 of the state that that's the correct answer. That's a pretty tall hill to climb...