The fact is that when the constitution was signed, citizens could own military arms, including cannon.
I think we should be able to purchase military weapons
of any level, upon proof of training and proof of secure storage. The Swiss have this arrangement, more or less.
My response was tongue-in-cheek; the privateers (private warships) were critical to the naval war. I think the Framers were still OK with that concept a few years after they saved their bacon...