After 45+ years of shooting traditional round ball muzzle loaders, this is the first time I have heard of someone deliberately wanting to "roll around" their lead balls to remove the sprue. Wouldn't hurt anything but I see no value in it either.
As Pahoo said, just use. Sprue up.
As for the cockeyed sprue making the shoot left or right.
Oh, well. It is do yer own thang game.