The Type 100 is a double barreled machine gun of Japanese origin. The weapon is gas operated and fed from an overhead magazine. An example can be seen at the Satria Mandala Museum in Jakarta.
The Type 100 and Type 1 weapons offer the advantage of two guns being mounted in the space occupied by one gun of the same size, thus saving weight in the gun and mount, and space in the plane. A small ammunition supply making frequent magazine loading necessary is a disadvantage, partially because of the advantages of the double barrel principle.
The operation for both barrels is housed in a single receiver. This is a single forging, milled to house the two separate actions. The magazine opening is cut out of the top of the receiver, the ejection slot out of the bottom. Each action has its own back plate. The gas piston group resembles the Bren light machine gun in design. The bolt is a steel forging that is well machined. The gas cylinder tube is constructed of seamless steel tubing and is threaded to the receiver at the rear. The trigger assembly is made up of two separate sear assemblies riveted to the pistol grip framework. Two pistol grips are located about 6 inches apart, the sears are connected to a horizontal trigger bar mounting a trigger on either end. Both guns may be fired by depressing either trigger. The magazine is the saddle-drum magazine type. Each side holds 50 rounds and feeds one gun. Each side has its own spring so that, in the event of a jam affecting one barrel, the other gun may continue to fire.
The Type 1 variant appears to be basically the same weapon as the earlier model, the Type 100. The Type 1 gun had a head or shoulder rest attached to it.