This isn't even true. The Constitution was already ratified by the time the amendments started to be considered.Madison "was worried about opponents who would think Congress would call up state militias and nationalize them. 'That can't happen,' said Madison," said Breyer, adding that historians characterize Madison's priority as, "I've got to get this document ratified."
Heller already hints at the answer on page 55."We're acting as judges. If we're going to decide everything on the basis of history -- by the way, what is the scope of the right to keep and bear arms? Machine guns? Torpedoes? Handguns?"
Do infantrymen get machine guns? Sometimes. Do infantrymen get handguns? Yes. Do infantrymen get torpedoes? No.It may be objected that if weapons that are most useful in military service—M-16 rifles and the like—may be banned, then the Second Amendment right is completely detached from the prefatory clause. But as we have said, the conception of the militia at the time of the Second Amendment’s ratification was the body of all citizens capable of military service, who would bring the sorts of lawful weapons that they possessed at home to militia duty. It may well be true today that a militia, to be as effective as militias in the 18th century, would require sophisticated arms that are highly unusual in society at large.