Cast iron
Cast iron is made from pig iron, which is the product of smelting iron ore in a blast furnace. Cast iron can be made directly from the molten pig iron or by re-melting pig iron, often along with substantial quantities of iron, steel, limestone, carbon (coke) and taking various steps to remove undesirable contaminants. Phosphorus and sulfur may be burnt out of the molten iron, but this also burns out the carbon, which must be replaced. Depending on the application, carbon and silicon content are adjusted to the desired levels, which may be anywhere from 2–3.5% and 1–3%, respectively. If desired, other elements are then added to the melt before the final form is produced by casting.
Cast bullet
A cast bullet is made by allowing molten metal to solidify in a mold. Most cast bullets are made of lead alloyed with tin and antimony; but zinc alloys have been used when lead is scarce, and may be used again in response to concerns about lead toxicity. Most commercial bullet manufacturers use swaging in preference to casting, but bullet casting remains popular with handloaders.