Yeah it does seem like we shot a lot trash and sporting goods, doesn't it. But why no iron? Well simple, availability. There is a lack of quality cast iron balls out there. And the cost is a bit prohibitive to set up to do your own iron ball casting.
It is quite simple to set up and cast lead or zinc. Zinc is especially nice as it can be done at home and gives a ball that is almost the same weight as an equivalant Iron ball.
Here is a zinc ball, for a 3.48 inch 6PDR.
Cut the sprue off and it weighs almost 6 lbs onthe nose.
I use the same type equipment for casting a zinc ball as I do for casting lead bullets.
Just the mould is a tad bit larger.
I recover my zinc balls and when they get dinged up into the pot they go. Can't do that with iron.
Zinc is also a bit less abrasive on the bore of my cannon.
I recently up graded my bore from pop can to 6 PDR