gun-metal

The beſt Guns are not made of malleable Metal, and cannot be made of pure Copper or Braß; but it is neceſſary to put in courſer Metals to make it run cloſer and ſounder, as Lead and Pot-metal. […] About 20l. of Lead is uſually put into 100l. of Pot-metal; but about 6l. is ſufficient to put into 100l. of Gun-metal.