MG Overheating Modern air-cooled belt-fed machineguns often have a rate of fire that exceeds the capacity of the barrel to cool itself, resulting in melted barrels. When firing suppressive fire, a 1 rolled on the Shooting roll indicates that the barrel has overheated. It must then be changed. If no barrels are available the gunner can either wait five rounds for the weapon to cool, or pour 4 quarts of water on the barrel. A third solution is to keep firing the weapon. On subsequent rolls in which the gunner takes none of the above remedial actions, any 1s rolled indicate the barrel has melted, ruining the gun until it can be worked on by the unit armorer.