What does blue mean on a gun?

Answer 1

Guns come in various finishes to prevent rust and corrosion. Various types can be nickeled, painted, enameled, blued, or others.

Guns that have been treated with "blueing" are the most common. They are the firearms you see with a black finish. The coating that they put on starts out as a blue-black liquid. Once the oxidation process is finished, it turns out more of a black color. Although, sometimes it can be a little brown or blue in color.

The condition of the blueing on the weapon can have an effect on the value.