Gunmetal, also known as red brass in the United States,[1] is a type of bronze – an alloy of copper, tin, and zinc.[2] Originally used chiefly for making guns, gunmetal was eventually superseded by steel. Gunmetal casts and machines well and is resistant to corrosion from steam and salt water,[3] and is used to make steam and hydraulic castings, valves, and gears, and also statues and various small objects, e.g. 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.
Gunmetal can also mean steel treated to simulate gunmetal bronze.[2] Bushings made of this metal are used in machinery.
The British Victoria Cross, the highest award for military valour, is traditionally known to be made using gunmetal from a cannon captured at the Siege of Sevastopol during the Crimean War. However, recent research has expressed some doubts over this theory, as it shows the source of early Victoria Crosses to be from Chinese cannons.[8]
The British Gwalior star medal, awarded to the British participants in the 1843 campaign against the Scindias is made of guns captured at the Battles of Maharajpur and Punniar, during the Gwalior Campaign.
Gun money, Irish late 17th century emergency coins, contains gunmetal, as worn and scrapped guns were used to make them, but also many other metals, in particular brass and bronze, as people donated pots and pans and other metal objects.