Gun metal is used for making guns and is also known as red brass. Gun metals are resistant to corrosion that is caused by steam and salt water. That’s why their composition includes metals which provides resistance to corrosion. Usually, gun metal is a type of bronze which is an alloy of copper, tin and zinc.

The major components in "Gun Metal" are

$\mathrm{Cu}:87\%$

$\mathrm{Zn}:3\%$

$\mathrm{Sn}:10\%$