The largest caliber gun ever made was the Schwerer Gustav, a German 80-cm railway gun. It was designed in the 1930s and used in World War II. It could fire shells weighing up to 7,000 kg (15,000 lb) a distance of 47 km (29 mi). The Schwerer Gustav was the largest-caliber rifled weapon ever built and fired the heaviest shells of any artillery piece. It remains one of the largest mobile artillery pieces ever built.