2nd Amendment was meant to stop the federal government from grabbing state militias to use in a federal army, anyway, because the slave states were worried about slave uprisings if their militias got depleted that way.

There are no private well-regulated militias in the US. Closest thing to what the Founders were arguing about is the National Guard. We're at least not enough of a joke so the National Guard is committing school shootings, but . . . .