Alloys

Gun metal is an alloy primarily used for making bullets and lighter flints. It is made of copper, tin, and zinc, with small amounts of lead. The alloy is strong and corrosion-resistant, making it ideal for these applications. - Shell metal is an alloy of tin and lead used for making shells. - Misch metal is an alloy of rare earth metals, primarily used in making flints, but not for bullets. - Monel metal is a corrosion-resistant alloy of nickel and copper, used in marine applications and not for bullets.
Therefore, the correct answer is Gun metal.