To minimize heating during rapid fire, the gun used a very heavy straight contour barrel, bringing its weight up to 35 pounds. Later versions added prominent finning to aid air cooling. The standard tripod mount with seat for the gunner added another 56 pounds. Despite the heavy barrel, the closed bolt mechanism would cook off shots if a round was left chambered in a hot barrel. This required that the gun be unloaded immediately after an extended burst of firing. During testing of the gun, it was found to be capable of firing extended bursts of over 1,000 rounds before the barrel overheated and bullets began to tumble out of control; upon stopping, the red-hot barrel cooked off four or five additional shots before cooling down.