Type 1 47 mm Anti-Tank Gun

The Type 1 47 mm anti-tank gun (一式機動四十七粍速射砲) was an anti-tank gun developed by the Imperial Japanese Army, and used in combat during World War II. The Type 1 number was designated for the year the gun was accepted, 2601 in the Japanese imperial year calendar, or 1941 in the Gregorian calendar.

History and development
The Type 1 47 mm Anti-Tank gun was accepted into service in 1942. The design originated as an improvement to the prototype “Experimental Type 97 (1937) 47 mm Anti-Tank Gun” (試製九七式四十七粍速射砲), which was tested between 1938 and 1939. The prototype weighed 567 kilograms with a barrel length of 2,515 mm, a traverse range of ±50 degrees and an elevation range of between minus 10 and plus 20 degrees, and a muzzle velocity of 730 m/s. The prototype was not accepted into service because it was considered to not have sufficient performance.

After the Nomonhan Incident, the Imperial Japanese Army started the development of a new anti-tank gun, considering that the Type 94 37 mm Anti-Tank Gun would likely be ineffective against the new Soviet tanks. The design was the first completely indigenous anti-tank gun design completed in Japan, and production was assigned to the Army's Osaka Arsenal. In terms of performance, the design was still somewhat inferior to advanced contemporary designs in western nations, but was considered suitable by the Imperial Japanese Army General Staff due to the anticipated lack of armor by the National Revolutionary Army of the Republic of China, and by the belief that Japan would face only light tanks fielded by the Allied nations in case of a more general war. The Type 1 47 mm AT Gun was introduced in 1942, and approximately 2,300 were produced.

Design
The Type 1 47 mm AT Gun was a relative modern design compared to other Japanese Second World war designs, being relatively light and easy to handle. As with many Japanese designs, it had a very low profile and was intended to be operated from a kneeling or prone position. The gun had a gun shield to protect the gunner. The carriage appears to have adopted a number of design features from the Soviet ZIK 45 mm anti-tank gun, a number of examples of which were captured by the Japanese during the Battle of Khalkhin Gol (Nomonhan) in 1939. It used a semi-automatic breech block with a horizontal sliding wedge. When the gun was fired the spent shell casing was automatically ejected, and upon loading a fresh shell, the breech block closed automatically. A hydrospring recoil mechanism was housed under barrel. The weapon had a split trail which opened to an angle of 60 degrees for firing to improve stability. Transport was by towing behind a truck or horse, via two steel disc wheels fitted with sponge rubber filled tires.

Ammunition
The Type 1 fired two types of shell: Type 1 APHE (Armour piercing high-explosive) and Type 1 HE (High explosive).

Type 1 APHE shell
The APHE shell weighed 3.37 pounds and used a Mark 2 base fuse, the complete round weighing 6.1 pounds. It had a small explosive charge of 0.04 pounds consisting of RDX phlegmatized with 10% Paraffin. The round also had a tracer.

Type 1 HE shell
The HE shell weighed 3.08 pounds and used the Type 88 instantaneous or short delay fuse with a complete round weighing 5.4 pounds. It contained 0.2 pounds of explosive, consisting of a small block of picric acid and a larger block of TNT.

Combat record
The Type 1 47 mm AT Gun was introduced to combat service only in 1943, and up until that time Japanese infantry had considerable difficulty even against the Allied M3 Stuart light tank in the Pacific War. However, by the time the Type 1 was available in any quantities, the M3 had been superseded by the M4 Sherman, against which it was only marginally effective.

The Type 1 47 mm AT Gun was issued to armored units as well as independent anti-tank units and was fielded in a wide variety of areas, but most notably Southeast Asia, and continued to be used with diminishing effectiveness until the end of World War II.

After World War II Type 1 47 mm AT Gun was used in Indonesian National Revolution by the Indonesian Army. In the Battle of Surabaya Dutch forces and British forces suffered moderate casualties among their convoy which consisted M3 Stuart and M4 Sherman.

Variants
The Type 1 47 mm AT Gun was also used as the main armament of the Type 97 Chi-Ha Shinhoto.