Sorry random throwaway account, but you are incorrect. After the revolution, during the Articles of the Confederation era (1780s), the national defense devolved to various state militias and this was continued into the early 19th century. Thus we see all of the various references in section 8 enumerated powers to calling up, paying, and directing the state militias when necessary but a key point was that training of the militias was a reserved state power. Unfortunately, the states were poor. Very, very poor. Providing a few cannon was within their power but not providing each and every rifle of these militias. The states argued, successfully, that if the militia members had the right to maintain their arms at home the burden of providing such would fall to the militia members and not the states. Training and practices of such militias was the 'well regulated' part of that amendment, btw. It was not a rhetorical flourish that existed nowhere else in the document but was in fact a key part of the amendment as understood at the time. The 2A is a way to enable the states to push the burden of providing a rifle (a useful tool most of them would have already) onto the citizens and avoid the creation of an expensive mandate for the states that they were ill-equipped to provide at the end of the 18th century. One can argue that interpretations and opinions regarding the meaning have changed, but the history is both well-documented and quite clear.

If you actually studied US constitutional history rather than getting your arguments from the side of whatever box your latest gun purchase arrived in you might know these things.