How much do the balls weigh?
From George's Round Ball Calculator , 0.420187 lbs in lead.
Thanks for that link. I'd seen that before, but forgotten it.
It pretty much answered the question at the root of my query.
I was curious as to what the balls weighed, and what alloy was used to cast them. I use wheelweights and my 1.125" balls come out significantly lighter than they would if cast from pure lead. The difference in weight is negligible in small-bore projectiles, but as the diameter increases it becomes more obvious. I use the WWs for economy, the lighter weight is (if anything) a plus.
My problem is that my powder/bullet scale only weighs up to 1500 grains. The balls I cast are too heavy so I have to weigh them on my postal scale which only has a resolution of ¼ ounce. Still, there was enough difference in weight for the postal scale to differentiate between WW and pure lead balls.
According to the calculator the 1.250" balls above would weigh about 6¾ ounces cast from pure lead, and 6½ ounces cast from WWs.
Of course this is all based on the assumption that they are, in fact, cast from a lead alloy. If they are zinc then this observation is irrelevant.