The purposes of the framers appears to be a well regulated militia, and that militia subject to "unlimited" control by congress. I agree this would mean congress could not dismantle or subvert the purpose of the militia, but having tight controls over the weaponry at their disposal when not in a state of current or imminent battle would not seem to so undermine it. After all, even the professional military have much, much more tightly controlled access to & tracking of firearms than is imposed in civil society. It is hard to credit an argument that would say militia could not reasonably & constitutionally mirror those same controls.