Wheel weights contain antimony, which should make the ball harder, but lighter then pure lead.
Not being a bullet/ball caster myself, I presume that you use a mold to pour the molten material in? The identicle size bullet/ball if made from wheel weights, should be lighter than pure lead, as antimony is harder, but not as dense as pure lead.
I would have thought that w/w's would make a better ball myself, leastwise for hunting.
