The "Type 14 Nambu" was designed in 1925 with the goal of simplifying manufacturing to reduce cost. It was chambered for the 8mm Nambu cartridge and held eight rounds in the single-stack magazine. It was officially adopted for issue to non-commissioned officers in the Japanese Army in 1927 and was available for purchase by officers. The Type 14 was an improved version of the Type A Nambu. As many as 400,000 Type 14s were possibly produced. Most Type 14s are marked with the month and year of production according to the year of Emperor Hirohito with his reign name abbreviated Sho from Showa left of the stamped date.
Later production models are distinguished by an enlarged, oblong trigger guard (which was introduced after Japanese soldiers reported difficulty in accessing the trigger while wearing gloves in Manchuria) and sometimes have a knurled steel cocking knob instead of the standard "slotted" cocking knob. An auxiliary magazine spring was added from mid-1940 to retain the magazine and aid the magazine follower. The safety is a level on the left side and locks the barrel and barrel extension as well as stopping the sear from moving. A redesigned cocking knob was implemented in 1944 in order to simplify production. The Type 14 also lacks the grip safety used on the previous models. The Type 14 could be equipped with the Type 90 tear gas grenade with use of a special attachment.
Pre-World War II Type 14s are well made with quality during wartime dropping. Machining marks, a lack of polishing, and thin bluing became more common as wartime shortages affected quality. The later Type 14s remained quite functional despite the decreased quality. Holster quality for the Type 14 also degraded as the shortages of critical raw materials forced a change from a leather holster to rubberized canvas.
Despite the looks of the gun, which have been described as one of the ugliest guns ever designed, (oddly enough, however, based off the German Luger, which is thought of as one of the most beautiful guns ever designed) one quality of the Type 14 caught the eye of William B. Ruger who had acquired a captured Nambu from a returning U.S. Marine in 1945. Ruger duplicated two Nambus in his garage, and although he decided against marketing them, the handgun's rear cocking device and the Nambu's silhouette were incorporated into the Ruger .22 semi-automatic pistol series, when in 1949 the Ruger Standard (and later Mark I, II, and III) pistols were sold to the American public.