Type 100 submachine gun

The Type 100 (一〇〇式機関短銃 Hyaku-shiki kikan-tanju) was a Japanese submachine gun used during World War II, and the only submachine gun produced by Japan in any quantity.

Designed and built by the Nambu Arms Manufacturing Company, the Type 100 was a robust, if unremarkable, submachine gun that was first delivered to the Imperial Army, in 1942. Japan was surprisingly late to introduce the submachine gun to its armed forces.

The Type 100 was a well made gun, but the 8x22mm Nambu round was underpowered, roughly the equivalent to the .380 ACP. Atypically for a submachine gun, a bayonet lug was fixed under the barrel.

Despite its shortcomings and complexities, the Type 100 had a high quality chrome plated barrel to aid cleaning and reduce wear. Some models also featured a bipod or a complicated muzzle brake.

Three variants of the Type 100 were produced during the course of the war; an early version with bipod and extendable bayonet lug, one with a folding stock for paratroopers (Approximately 200 with the folding stock were made as it weakened the weapon's structure in combat situations) and a 1944 version that was greatly simplified in order to hasten production at a time when Japan was being pushed into retreat across the Pacific theatre and demand for submachine guns was at an all time high. The 1944 variant was slightly longer, featured simple iron sights. Corners were cut in production, leaving many Type 100s with roughly finished stocks and poorly welded parts. Despite this, the Type 100 is quite light, low recoil and accurate.

Despite these simplifications, Japan lacked the industrial infrastructure to produce sufficient quantities of the Type 100 to stem the rapid Allied advance. By 1945, 30,000 had been built, a comparatively low number to the 1,300,000 plus Thompson submachine guns built by the US.