The .500 Nitro Express is a rifle cartridge designed for hunting large and dangerous game animals in Africa and India. This cartridge was primarily designed for use in double rifles though various single shots were produced on the Farquarson action and at least one major company (Heym) produced it in bolt-action configuration. It was commonly available in two lengths: a 3.00 in (76 mm) and a 3.25 in (83 mm) version.