Gun Metal Castings is an alloy made primarily of copper and zinc. The proportions of the copper and zinc are varied to yield many different kinds of brass. Basic modern brass is 67% copper and 33% zinc. However, the amount of copper may range from 55% to 95% by weight, with the amount of zinc varying from 5% to 40%.
Lead is commonly added to brass at a concentration of around 2%. The lead addition improves the machinability of brass.
However, significant lead leaching often occurs, even in brass that contains a relatively low overall concentration of lead.
Uses of brass include musical instruments, firearm cartridge casing, radiators, architectural trim, pipes and tubing, screws, and decorative items.