Or, take another tack. At the time the 2nd Amendment was written, it was protecting (note, protecting not granting) our right to own exactly the same weapons as our military had at that point. So it could be construed as to protect our right to be armed equally as the military...
My favorite point to make, when a discussion goes down this path, is to remind everyone of the US Constitution, Article 1, Section 8 - Letters of Marque and Reprisal. The government, in its enumerated powers (not even the Bill of Rights), was granted permission to contract with privateers... people who owned their own BATTLESHIPS of the day! A Ship of the Line back then could easily be carrying over 300 cannon, and the Constitution acknowledged and accepted their existence in private hands of US citizens.
(They were mostly needed to combat the Barbary Coast Pirates, Muslims who were taking US and British ships and enslaving their crews around the Mediterranean. This is the reason for the lyric "to the shores of Tripoli" in the Marine Corps Hymn. Tripoli, Libya. Muslim slavery. The more things change, the more they stay the same.)