[Slipdigit]

I understood that the size of a gun in "pounds" derived it's name from the weight of a spherical iron ball that would fit into the gun and was a holdover from the days of sail, when the actually projectile did weigh a given amount. In modern times, it actually had nothing to do with weight of the actual projectile used. Thusly, a round solid ball of iron, 57mm in diameter would weigh approximately 6 pounds and a 40mm, 2 pounds, etc.

Am I incorrect in this assumption? Math and I are not good friends.