Numerous books and articles have been written by historians, scholars and theorists since the end of World War II on the flaws in the Japanese administration’s control in their manufacturing and production methods such as universal standardization. This analysis is not intended to examine such findings and conclusions. It is to present a non-political chronicle of progress in the continuum of “fine tuning” a certain machine gun series for improvements and final attempts at simplification to maintain operating reliability of the product. The changes and modifications were implemented when the unavailability of raw materials were diminishing, the loss of skilled labor due to events of the time and the continued threat of an aggressive Allied Nations.

The Type 99, [1939], light machine gun and its predecessor the Type 96, [1936], light machine gun were near twins with many identical features. Colonel Kijiro, inventor of these weapons had shown determination throughout his career to design improvements that would not only meet certain combat demands, but also make the manufacturing process less complicated, time consuming and reduce costly procedures.

The produced quantities alone of the Type 96 weapon indicates certain acceptance in its success while being manufactured by three separate contractors who together produced some 15,000 weapons during the five year period. ( Production data is taken from quantitative specimens as recorded in the author’s 50+ year data base collection of serial numbers and date inscriptions of Japanese small arms ordnance.) However progression was not without fault and delays. The lack of precision work in their manufacturing process prevented interchangeability of parts requiring hand fitting and finishing. This resulted in the added necessity to serial number most all parts.

During the 5 year production tenure of the Type 96 light machine gun before conversion over to the Type 99 light machine gun production, changes were being made within each manufacturer individually and some not necessarily being shared with the entire production group for a common goal. Samples show variations in casting and machining techniques such as in trigger housings and in the stock and tripod pin areas. Stock skirts and magazine levers were different.

Along with periodic improvements such as relocation of the windage knob and a one-piece aperture made to the rear sight, major changes started to occur in early 1939 to the Type 96 weapon in the Kokura Army Arsenal’s production. As detailed in a previous article on the subject, changes were made to the sear safety bar, alternate threading at the barrel muzzle to accommodate a new flash suppressor design, ejection port cover, barrel cooling fins, and added mass to receiver. From late 1942 through 1943 changes continued. Barrel locking pin configuration with shim stock provision for head spacing, barrel pin shielding, ejection port and magazine spring loaded covers, gas regulator plug, bipod latch plate shield and addition of a monopod to the buttstock. All of these features would eventually be incorporated into the new Type 99 light machine gun.

The Type 96 weapon design using a light powered 6.5 mm rifle cartridge had experienced problems with mechanics of the gun. Among the problems was the need to lubricate the cartridges at feeding. Although some improvements were made, a more flawless design was necessary for the use of a new and more powerful 7.7 mm cartridge. This was the primary and most important change between the two machine guns.

In the beginning Japanese observations in World War I, through the 1932 Manchurian conflict and the 1937 war with China dictated a clear need for advancement in small arms weaponry. The 1937 Comintern Pact with Germany and Italy increased needs to reform this position. The prevailing and major problem was the then current use of the 6.5 mm service cartridge. It was not designed for intentional use in machine gun systems and compounded the problem with inadequate long range performance especially for aircraft adaptation.

The Imperial Japanese Navy was successful with the British rimmed .303 caliber cartridge in their imported British Lewis and Vickers machine guns. They introduced a new semi-rimmed cartridge in 7.7 mm for first use in their licensed Vickers weapons. Both gun and ammunition was designated as Type 89, [1929].

The army’s development with ammunition was followed by adoption of Type 92, [1932], a semi-rimmed cartridge in the 7.7 mm caliber and specifically to meet machine gun application. The first use and adoption was in the Type 92 heavy machine gun. This caliber cartridge was further refined in a rimless configuration and first used in their Type 97 tank machine gun which emanated from the Type 91 series machine gun chambered for the Type 38, [Arisaka], 6.5 mm rifle cartridge. The new rimless cartridge was adopted in 1939 as Type 99.

The new Type 99 light machine gun chambered for the 7.7x58 mm cartridge, was first produced in 1940 by Colonel Nambu’s associate firm Chuo Kogyo KK. In 1941 both Nagoya Army Arsenal and the Private firm of Hitachi Heiki KK were producing the weapon with the fourth manufacturer, Kokura Army Arsenal, starting production in 1942. Although production by a fifth manufacturer in Japan was formulated, it did not take place due to turn of events in 1943/44 when the Allied nations offensive in the Pacific and Eastern front put Japan on the defense prompting the need to review ordnance strategies and priorities.

Although some variances did occur, there were no noticeable operational/maintenance changes to the Type 99 until 1943 when improvements were made in the early year by the Hitachi firm who began using split pins for parts assemblies and modified the gas piston housing by drilling a hole in back of the gas regulator for cleaning the barrel port. A spring clip cover protected the access hole. Some weapons, which were specifically tested and fired for automatic function and endurance, were inspector stamp coded on the weapon. Testing included headspace adjustment of which after acceptance, the barrel nut was pinned in place.

Along with continuous advance of the Allied nations in their thrust toward the Japanese homeland, came the air bombing raids in 1944/45. By the fall of 1944 production and quality started to diminish in the production of small arms ordnance. The Type 99 light machine gun was among small arms being scaled back in favor of aircraft and associated machine gun production. By October 1944, Hitachi Heiki KK the largest producer of the Type 99 weapons began to make changes toward a “need only” policy to enhance simpler and faster production.