Fluting (firearms)

G22 of the German Army with a fluted barrel.
Closeup of PGW Timberwolf action with a helically fluted bolt.

Fluting is the removal of material from a cylindrical surface in a firearm, usually creating grooves. This is most often the barrel of a rifle, though it may also refer to the cylinder of a revolver or the bolt of a bolt action rifle. In contrast to rifle barrels and revolver cylinders, rifle bolts are normally helically fluted, though helical fluting is sometimes also applied to rifle barrels.