Gunmetal, also known as red brass in the United States, is a type of bronze – an alloy of copper, tin and zinc. Proportions vary by source, but 88% copper, 8-10% tin and 2-4% zinc is an approximation. Originally used chiefly for making guns, it was eventually superseded in this department by steel.
Gunmetal, which casts and machines well and is resistant to corrosion from steam and salt water, is used to make steam and hydraulic castings, valves, gears, statues and various small objects, such as buttons. It has a tensile strength of 221 to 310 MPa, a specific gravity of 8.7, a density 8,719 kg/m3, and a Brinell hardness of 65 to 74.