[BJones12]

It is. The US defines a firearm as "Any weapon... which will or is designed to or may readily be converted to expel a projectile by the action of an explosive" and definitions in other countries are similar. Both a pistol and a ship-mounted cannon are firearms.

[Rebelgecko]

I thought if it uses black powder it isn't (federally) a firearm? IIRC felons can own black powder guns, you can have them shipped to your door, etc

[klooney]

Cannons are legal to own, which is a little wild

[lazide]

To be fair, it’s hard to make a 2nd amendment argument that doesn’t allow private ownership of muzzle loading black powder cannons.

They haven’t exactly featured prominently in drug land/gang movies either.

[injb]

US federal law excludes antiques from this, antiques being defined as 1898 or older.