| 12.7 cm/50 Type 3 naval gun | |
| Origin: | Japan |
| Type: | Naval gun |
| Is Ranged: | YES |
| Is Artillery: | YES |
| Service: | 1928—1966 |
| Used By: | Imperial Japanese Navy Soviet Navy Republic of China Navy |
| Wars: | World War II |
| Design Date: | 1926—1927 |
| Number: | approximately 700 |
| Length: | 6.483m (21.27feet) |
| Part Length: | 6.265m (20.554feet) (length of bore) |
| Cartridge: | separate-loading, bagged charge |
| Rate: | 5–10 rpm |
| Max Range: | 18400m (60,400feet) |
| Breech: | Welin interrupted screw |
| Elevation: | depended on mount |
The 12.7 cm/50 Type 3 naval gun was a medium-caliber naval gun of the Imperial Japanese Navy used during World War II. It was the standard weapon for Japanese destroyers between 1928 and 1944 (except the Akizuki and Matsu classes). It has been credited as a true dual-purpose gun, but this was more a nominal capability than real, as its bag propellant and need for hand ramming required the gun to be loaded at elevation angles of 5–10°. This dropped its rate of fire to a relatively slow 5–10 rounds per minute, and its training speed of only 6° per second meant that it had a great deal of difficulty engaging enemy aircraft with any chance of success. After the end of World War II, the gun was exported via the two Japanese destroyers ceded as war reparations to the Soviet Union[1] and the Republic of China.[2]
The 50-caliber Type 3 gun was of built-up construction, originally with three and later two layers with the usual breech ring and breech bush.[3] It used a Welin interrupted screw breech and powder bags, unusual for guns of that caliber. The shell was fuzed manually on the loading tray before being rammed by hand and could only be loaded at elevations between 5° and 10°. All mounts used pusher-type shell hoists, but the powder bags were passed by hand.[4]
These guns were first used in the twin gun Model A turret on the revolutionary s. These were the first weatherproof, splinterproof and gas-proof enclosed gun turrets ever mounted on a destroyer.[5] Guns in twin mounts were in individual cradles and could elevate separately. All twin gun mounts weighed approximately 32t. All mounts could traverse at 6° per second and could elevate at a rate between 6° and 12° per second although speeds up to 27° per second have been reported.[3]
The twin gun Model A mount was fitted with a 9- gun shield. Its guns could depress −5° and elevate to +40°. These mounts were deployed on the first ten Fubuki-class destroyers. The twin gun Model B mount had its elevation increased to 75° and was fitted in the rest of the Fubuki-class as well as the destroyers.[3] In order to save weight its gun shield was reduced to in thickness, but this proved too thin to withstand heavy seas and was later reinforced. The first four of the used the Model B mod 2 mount although how it differed from the earlier Model B mount is unknown. The last two of the Hatsuharu class, the,, and destroyers used the Model C which reduced its maximum elevation to 55°, but could depress to −7° and was supposedly lighter than earlier models.[4] The Model D used by the and the destroyers retained the depression limit of the Model C, but elevation returned to the 75° of the Model B.[6]
The Type A single mount could depress −7° and elevate to +75°,[4] but the Type B reduced the maximum elevation to 55°.[3] Both mounts weighed approximately 18.5t.[6] The Type A was fitted on the Hatsuharu class and the Type B on the Shiratsuyu-class destroyers.[3]
The gun normally fired a high-explosive shell, an illumination shell or an incendiary shrapnel round () intended for anti-aircraft use. All of these shells weighed and used of 30 DC propellant. After 1943, a flat-nosed anti-submarine shell also became available. This had a minimum range of 800m (2,600feet) and a maximum range of 4300m (14,100feet). A new, heavier, but more streamlined, high-explosive projectile with a range of 23025m (75,541feet) was under development when the war ended.[6]
| Shell name | Weight | Filling Weight | Muzzle velocity | |
|---|---|---|---|---|
| Common Type 0 high-explosive | ||||
| Common Type 1 high-explosive | ||||
| Illumination | Not applicable | |||
| Anti-submarine | ||||
| New Type high-explosive Projectile |