[arcticap]

You're not the only one who casts balls using wheel weight lead.
However, why use such a tight combination?
I wonder just how much sooner the rifling at the crown will wear out.
Some folks cone their crown which helps to make loading a little easier but even then harder lead may still cause extra wear where the PRB's first engage the rifling. They say that crowning doesn't affect accuracy but I wouldn't choose to cone because there's no guarantees.
The folks who cast using harder lead are more often the smoothbore shooters because their crown doesn't have any rifling to wear out and they use balls that more undersized along with thicker patches.
And some folks who shoot minies have mentioned that their barrels do lose accuracy over time which may be caused in part by barrel wear even if pure lead is used.
I guess that it depends at what distance folks are shooting at and how much of an accuracy difference there is by switching to a smaller PRB combination if using wheel weight lead balls.