“...I’m now fairly convinced that that is exactly what the founders gave us: an intentionally vague pronouncement designed to force the question into the future, to ensure it would be repeatedly reevaluated to keep up with changing weaponry and circumstances. “
I don’t think it was designed to “force the question into the future”. I think they wanted to guard against future tyranny (they had just come out of a war), but couldn’t bring themselves to write “A well regulated Militia being necessary to overthrow the government we just established if it becomes tyrannical, the right of the people to keep and bear Arms, shall not be infringed.”
“But they didn’t tell us how much firepower citizens should be allowed to have. “
Yes they did. They said we could have militia weapons, like the ones the army has.
Shall not be infringed is definitely not vague.