Machine guns then diverged into heavier and lighter designs. The later model water-cooled Maxim gun and its derivatives (the MG 08 and the Vickers gun, as well as the American Browning Model 1917 machine gun), were all substantial weapons. The .303 inch Vickers, for example, weighed 33 lb (15 kg) alone and on its tripod mount the total weight was 50 lb (22.7 kg). The heavier designs could, and in some cases did, literally fire for days on end. The need was to be able to cut down, potentially, thousands of charging soldiers. The heavy machine gun was mounted on a tripod and was often water-cooled; a well-trained and well-supplied crew could fire for hours on end. Carefully positioned heavy machine guns could stop an attacking force before they reached their objectives.