In our experience, we could not get hardcast bullets to shatter on hard/frozen beef bones...they would shed weight but not shatter as such. When bullets mushroomed in our tests, bullets that used lots of tin out performed bullets hardened by other means. Med. hard cast bullets w/lots of tin would mushroom nicely and retain their weight best, unfortunately tin adds considerably to the cost. Any bullets I make for hunting contain lots of tin as a consequence of these tests. Even when working with a hard alloy such as linotype I add tin as it makes it more maleable(sp?).