"Lightening holes are holes found in various firearm components used to make the weapon lighter in weight as well as increase the ruggedness and durability. They are usually made by drilling holes, pressed stamping or machining and can also save strategic materials and cost during wartime production."@en . . . "Lightening hole"@en . "Lightening holes are holes found in various firearm components used to make the weapon lighter in weight as well as increase the ruggedness and durability. They are usually made by drilling holes, pressed stamping or machining and can also save strategic materials and cost during wartime production."@en .