Last I knew, CA required "certification" that ammunition was lead free (well, <1% lead), and that certification had only been granted to commercial firms.
Casting with any of the alternate materials available requires changes in casting temps/techniques and in expectations. Tin was particularly problematic: I had trouble getting consistent weights with all the alternates I tried (though further refinement in casting techniques might have reduced or resolved this), but tin was the worst. The lead-free metal offered by Rotometals (an alloy of bismuth/tin/antimony IIRC) required casting at lower temps (<500 degrees), paying particular attention to mould temperature, and longer waits before cutting the sprue. At longer ranges I suspect the velocity loss is going to be a significant factor.
Performance-wise, all alternates were harder and less-dense than lead. As a consequence, they all shot lower and lost velocity faster than lead. No obturation was noted: balls shot into a snowbank and recovered in spring mic'd the same as when fired.
I tested several alternates while doing some control shooting of feral hogs and whitetail deer. My test gun was my .50 cal GRRW Leman. Tin showed some deformation but minimal expansion when bone was struck. Rotometals' offering basically disintegrated when major bone was struck. Both performed adequately (no game was lost) but I hunt close: out of a dozen animals, none were taken past 25 yards.
