[El Gato]

The second half of the Amendment reads "the right to keep and bear arms shall not be infringed", but how far does that right go?

At the time it was written, it was not unusual for individuals to own cannon and/or cannon armed ships.

[Vicomte13]

"At the time it was written, it was not unusual for individuals to own cannon and/or cannon armed ships."

It was unusual, because those things are quite expensive.
Only important, wealthy figures did, and the American Colonies/early Federal period states were certainly run by the gentry.

At any rate, there was, and is, a fundamental difference between a portable mass-casualty weapon like a machine gun and an armed privateer. There's certainly a difference between a cannon and a personal anthrax bomb.