Proportions of its metals vary. 88% copper, 8-10% tin and 2-4% zinc is usual.
Originally it was used for making cannons. Guns are now made of steel. Gunmetal is easy to cast and work on a lathe. It resists corrosion from steam and salt water. It is used to make steam and hydraulic castings, valves, gears, statues, and various small objects such as buttons.