Type 100 submachine gun
|100 Shiki Kikan-tanju|
Type 100 (1944)
|Place of origin||Empire of Japan|
|Used by||See Users|
|Wars||Second Sino-Japanese War,
Second World War,
Indonesian National Revolution,
First Indochina War,
Korean War (limited usage),
Vietnam War (limited usage)
|Variants||Type 100/40 (with solid stock)
Type 100/40 (with folding stock)
Type 100/44 (with solid stock)
3.8 kg (8.4 lb) (1942, empty)3.4 kg (7.5 lb) (1944, empty)
4.4 kg (9.7 lb) (1944, loaded)
|Length||890 mm (35.0 in) (1942)
900 mm (35.4 in) (1944)
|Barrel length||228 mm (9.0 in) (1942)
230 mm (9.1 in) (1944)
|Rate of fire||450 rounds per minute (1942)
800 rounds per minute (1944)
|Muzzle velocity||335 m/s (1,100 ft/s)|
|Effective firing range||100-150m|
|Feed system||30-round detachable curved box magazine|
The Type 100 submachine gun (一〇〇式機関短銃 Hyaku-shiki kikan-tanjū?) 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 third variant was a folding version of the early model, sometimes referred to as the Type 100 Navy, made for parachutists.
Designed and built by the Nambu Arms Manufacturing Company under a low-priority military contract, the Type 100 was a submachine gun that was first delivered to the Imperial Army in 1942. Japan was surprisingly late to introduce the sub-machine gun to its armed forces — a few models of the SIG Bergmann 1920 (a licensed version of the German MP 18) were purchased from Switzerland in the 1920s. These were examined and copied, with significant changes. In 1942 the Type 100 SMG was first delivered for service, used by Japanese marines during the invasion of Southern China.
The Type 100 was typical of the class of simple, inexpensive, wartime submachine guns produced by all military powers—designed for maximum ease of production. It is based on a simplified Bergmann MP18, modified for the 8mm Nambu round. It was an automatic-only, air-cooled, blowback weapon firing from an open bolt and feeding from a side-mounted, 30-round detachable box magazine. The barrel was given six-groove, right-hand-twist rifling. Unusually for a submachine gun (but typical of Japanese weapons of the era), a bayonet lug was fixed under the barrel, in this case with a heavy bar and lug. Some of these models featured a bipod, and others featured a complicated muzzle brake.
The Type 100 had a chrome-plated bore to help fight corrosion in Asian jungle conditions. Its complex ammunition feed included a feature whereby the firing pin would not operate until the round was fully chambered; frequent stoppages in firing were experienced in the field. The round was the underpowered and relatively ineffective 8x22mm Nambu pistol round. The curved box magazine extending from the left side made for poor weapon balance when full. The sights were canted to the left.
Two basic performance variants of the Type 100 were produced during the course of the war: the Type 100/40 was an early version with bipod and heavy bayonet lug, judged unsatisfactory because of frequent jamming of the feed mechanism, and the Type 100/44 was a simplified 1944 version that had a higher rate of fire and much greater reliability. A third variant was a lightened version of the early Type 100/40 design which was delivered with a folding stock for navy paratroopers.
The Type 100/40 was complex, designed with little consideration for mass production. Its sights and feed mechanism were overly complicated. Its rate of fire was some 350 to 450 rounds per minute, and it jammed frequently. The 8×22mm Nambu pistol cartridge it fired was rather underpowered, compared to contemporary military pistol cartridges such as 9mm parabellum and .45 ACP. In practice, the bayonet was not widely used. Some 10,000 were produced by the Kokura Arsenal for the Imperial Japanese Army.
A folding version of this model was made for paratroops, designed with a folding stock for lighter weight. The reliability was not improved, and the folding stock proved less suited to close combat than the solid stock which stood up better in a buttstroke. Some 6,000 to 7,500 were made at Nagoya Arsenal and delivered primarily to the Imperial Japanese Navy for its marine paratroops (Rikusentai), but also to Army paratroops—Teishin Shudan—who used them in February 1942, during the Battle of Palembang, on raids against oilfields. Navy paratroops used the weapon in the first months of 1942 during the Battle of Manado and the Battle of Timor.
The late war variant Type 100/44, the simplified model, was designed in answer to suggestions coming from field units, and to hasten production at a time when Japan was being pushed into retreat across the Pacific Theater of Operations—demand for submachine guns was at an all-time high. The 1944 variant was slightly longer, with simple iron sights and a greatly simplified muzzle brake consisting of two ports drilled in the barrel. The bipod and the large bayonet mounting bar were eliminated, with the bayonet fitted to the barrel instead; consequently, the muzzle protruded more from its perforated jacket. Corners were cut in production, leaving many Type 100s with roughly finished stocks and poorly welded parts. The relatively weak 8 mm round remained the same, but the rate of fire was significantly increased, to 800 rpm. The resulting Type 100/44 was quite light, with low recoil, and demonstrated good reliability and satisfactory accuracy for close-range work. Some 8,000 were made by Nagoya Arsenal.
Despite these simplifications, Japan lacked the industrial infrastructure to produce suitable quantities of the Type 100. By 1945, only 24,000 to 27,000 had been built.
Use in combat
Whilst the Type 100 proved to be an effective and reliable weapon in close quarter fighting, perceived lack of requirement for SMGs and Japan's poor industrial capacity meant that only around 27,000 were ever produced. As a result of this, when the weapon was issued to regular combat units only officers and some NCOs received it; the Type 100 was never a common battlefield weapon. Special forces units are known to have been prioritized for reception of the weapon due to the nature of their operations; however, some American service personnel did report encountering the weapon in the Pacific Islands late in the war. Additionally, no Japanese soldier was ever equipped with the weapon until late 1941, and it was not produced in any significant quantity until 1943 — a point at which the manufacturing quality of Japanese weapons had already begun to deteriorate.
- Republic of China: captured examples were pressed into service during World War II and the Chinese Civil War
- China: Used by Chinese troops in the Korean War.
- Malaysia: Used by Malayan Communist Party troops in the Malayan Emergency.
- North Korea: Used by North Korean troops in the Korean War.
- Republic of Korea: Limited, used by Republic of Korea Armed Forces in the Korean War.
- Vietnam: Used by Viet Minh soldiers in the First Indochina War
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