Melt the lead free balls down, and recast them in a smaller mold. But don’t make the same dumb mistake the manufacturers of those balls made. Remember alloy balls molded in a mold come out larger than they would be if they were molded from lead in the same mold.
And then once you have the mold you can easily mold lead free balls from lead free pewter obtained from your local second hand store. They usually have a bunch of mugs, and goblets, that are food grade. Most are engraved as a trophy which reduces their price considerably.
Hungry Horse