This book contains details of machine guns ranging from light-support weapons and squad automatic weapons to general purpose machine guns, sustained fire machine guns and large calibre guns used in heavy support and anti material roles. The purpose of this book therefore inclusion as a machine gun depends on whether the gun can feed ammunition belts, whether the barrel is readily detachable (enabling fire to be sustanied) and whether the action fires automatically from the open-bolt position to prevent the effects of barrel heating a chambered round before it can be struck by the firing pin.