[Slamfire]

I read that early cannon balls were made from stone.

While a lead projectile would be heavier for the same diameter and carry further, that would not be an advantage for Civil War and earlier cannon.

Civil War cannon have sights, many earlier ones don't. A civil war Napoleon could hit a pickup truck at 500 yards, and that was about it. Cast iron cannon balls could hit as far as you could see and that was the limit of the accuracy of the things.