
It is believed that less than 10,000 of both models were produced. There is no record of their appearance against US forces in the South Pacific nor against British troops in Burma. The Japanese Type 100/40 with bayonet bar.The only recorded use of these weapons in combat was in the Japanese parachute attack on the Dutch oilfields in Java in 1942, when they were reported to have been highly effective. Mechanically there was little of note they were a simple blow back weapons working on familiar principles. The infantry models were sometimes fitted with a small bipod. Both were fitted with bayonet bars under the barrel, and the interior of the barrels was chrome plated. The Model 40 came in two patterns, one for infantry use with a solid stock and one for Airborne troops using a hinged folding stock. Although far from perfect its performance was good enough to stimulate interest in the weapon, and this led to development of an improved version, the Model 1944, but work began too late and was carried out too slowly to allow stocks to be built up.

It was a modified Swiss Solothurn S1-100, which was also used by the German and Axis armies in Europe. The Type 100, Model 1940, was issued in 1941-42 in limited numbers.
