Gun Metal

Formerly an alloy of 90 parts copper and 10 parts tin, often called bronze or bra . The old 6 and 12pounder field-guns and the howitzers were made of this alloy. Later, a fine quality of cast-iron, obtained by special treatment and used for casting the 8, 10, 15, and 20-inch Rodman smoothbore guns. Now, low steel, containing ab. 0.5 per cent of carbon.