Militia and State powers
Was inspired to a separate post by a comment from J. Norman Heath, who indeed wrote "the" article on the issue, "Exposing the Second Amendment" 79 U.Det. Mercy L.R. 39 (2001). He examines early Supreme Court decisions, and concludes that the Court left the States with very little in the way of power. Maybe some, if Congress did absolutely nothing. But once Congress acted, no matter how inadequately, its power became near-absolute, with States able at most to enforce the Federal legislation (and some Justices thought even that was too much).
Remember that historically the militia was to be the mainstay of national defense. As Madison said in Federalist 46, we'd have 25,000 troops at absolute max (in practice, we had more like a thousand or two), and 600,000 militiamen. The standing army would hold off an invader until the militia could rally and do the real fighting. You wouldn't want part of your main defense establishment carrying .65 muskets and others .75 caliber, or one part trained to one drill book and the other trained to another that had different orders, one organized into 1600 man regiments with two battalions and another with 1000 man regiments and no battalions (OK, so they had that in the Civil War, regular vs. volunteer regiments).
Question: might the unorganized militia today be in the state that the Court mentioned when it said that a different case would be presented if Congress entirely failed to act? At the moment, Federal legislation defines who is in the unorganized militia, and as I recall provides for its calling out, but gives it no standards for armament, officers, organization, or training.