The Framers have addressed your question, at least implicitly. Article I, section 8, clause 11 authorizes congress to issue "Letters of Marque and Reprisal". At the time of the founding, these were warrants authorizing private citizens to take action against enemy nations.
The very strong implication was that it was perfectly reasonable for individual citizens, or groups of individual citizens, to possess weapons at least comparable to, if not equivalent, or even superior to those of enemy nations.
Even though congress has never used this power, the thinking behind it is pretty clear to anyone who can read common english. The lawyers who will spend days and months arguing over how many angels can dance on the head of a pin have convinced themselves that the 2A has a much lesser meaning today. But it does not take much thinking or study for a reasonable man to convince himself that the original meaning of "keep and bear arms" was quite broad.