The was a Japanese submachine gun used during World War II and the only submachine gun produced by Japan in any quantity. It was made in two basic variants referred to by American and British observers as the Type 100/40 and the Type 100/44, the latter also known as the Type 100 (simplified). A small number of the earlier version were converted into using folding stock, sometimes referred to by the Allies as the Type 100 navy, which was made for parachutists. Prototypes Japan was late in introducing the submachine gun to its armed forces. Although around 6,000 models of the SIG Bergmann 1920 (a licensed version of the German MP 18) and a few Solothurn S1-100s were purchased from Switzerland and Austria in the 1920s and 1930s, and were used in the invasion of China in 1937, mass production of a native submachine gun did not begin until 1944. While the western European imports were used, Japanese development of submachine guns had stalled. After earlier prototypes designed and built by the Nambu Arms Manufacturing Company, the Experimental Model 1 and Experimental Model 2 submachine guns, proved inadequate, new requirements were formulated in August 1937 by the Army. The new simpler design was based on the imported European "Bergmann type" submachine guns, which had been used effectively in both Battles of Shanghai by Japanese marines. This led to the development of the Experimental Model 3 submachine gun in 1938. The earliest version was known as Model 3A, but after some changes Model 3B was introduced in April 1939. It received generally positive results in testing and it was recommended to produce a batch of 200 weapons for military tests with infantry, cavalry, and reserve units. Further requirements were made for increased accuracy and a way to mount the standard Type 30 bayonet. A portion of the weapons for cavalry units were mounted with a bipod and a sight up to 1,500 meters to assess it capabilities in comparison with the bulky Type 11 light machine gun. Early version In November 1939 came the release of the Type 3C, which included a double-slot muzzle brake. After almost full completion of the testing cycle of this version it was adopted by the Imperial Japanese Army in the summer of 1940 as the Type 100 submachine gun (known in western literature as the "Type 100/40"). However, no major order was made for the