Brownells Superhard Bullet Casting Alloy. Ingots weight roughly 5 pounds. This alloy consists of 70% Lead and 30% Antimony. A great source for hardening up your recovered lead and is easier to melt than pure Antimony. Superhard Alloy will met at around 745° F. Brinell hardness is difficult to determine on Superhard so it sold based on the percent of Antimony. Made form virgin metals, not from scrap, ensuring you are adding clean alloy. Sold by the ingot, weights are approximate.