Naval Base Guam Japanese Type 96 Anti-Aircraft Gun
Posted by: 
SaltyDog20
N 13° 25.738 E 144° 38.938
55P E 245431 N 1485788
A preserved AA gun manufactured by the Japanese during WWII and put into use as both an AA and AT weapon during the war.
Waymark Code: WMMJ7C
Location: Guam
Date Posted: 09/26/2014
Views: 5
Taken from Wikipedia:
In 1935 the Imperial Japanese Navy decided to replace the earlier 40 mm Vickers "pom-pom" guns with a 25 mm Hotchkiss design. A party of Japanese officers and engineers traveled to France to evaluate the design in 1935 and an order was placed for a number of guns and mounts for evaluation. Firing tests of these guns were conducted at Yokosuka Naval Arsenal in 1935. The first few weapons were built in France under the designation “Type 94” and “Type 95”, with the mass production model produced at the Yokosuka Arsenal being designated “Type 96”.
The Japanese made a number of minor changes to the original Hotchkiss design and production process, changing some components from forgings to castings to simplify production and replacing the simple conical flash suppressor with a Rheinmetall-type design. A submarine-mountable version of the gun was also produced, which made extensive use of stainless steel.
The double mount type was the first to enter service, with triple mounts following in 1941 and finally single mounts later in 1943.
The Type 96 25mm Gun is a simple air-cooled gas operated design. The barrel is a forging screwed into the breech mechanism. Additional support is provided to the breech end of the gun barrel by the finned cooling jacket. The barrel is changeable, but the operation required two men and special tools to complete, and took a trained crew approximately five minutes. By adjusting the gas valve setting it was possible to vary the rate of fire between 200 and 260 rounds per minute, with 220 rounds per minute being the standard setting.
The gun mounts were normally provided with one of three gun sights:
A Le Prieur mechanical lead computing sight
An open ring sight
An etched glass optical ring sight
Land mountings and all single mountings all used the single open ring sight. The Type 95 sight was used on ship-based multiple mounts, in the case where the mount has a powered drive linked to a fire director it was used as a backup.
The Type 95 sight was originally designed with a maximum target speed of 600 kilometers per hour; however, experience showed that aircraft often exceeded this speed. To compensate for the problem a ring was added to the sighting telescope to provide an additional offset for the speeds up to 900 kilometers per hour.
The gun was normally used without a gun shield, although some multiple mounts on Yamato-class battleships were fitted with a Ducol (High tensile steel) shields. Many ship based mounts also had splinter shields.
In interviews conducted by the U.S. Naval Technical Mission to Japan after the end of the war, Japanese military personnel cited it as the most reliable Japanese anti-aircraft weapon, but second in effectiveness to the Type 98 100 mm anti-aircraft gun. The Type 96 was most effective when used at ranges of 1,000 meters or less. Japanese military estimated that it required an average of 1,500 rounds to down an aircraft at a height of 1,000 meters and a range of 2,000 meters and that fire beyond that range was completely ineffective. Later in the war when ammunition supply was restricted, firing was held until the targets were within 800 meters range this dropped to a low as seven rounds per aircraft according to Japanese sources. The Type 96 was a mediocre weapon, hampered by slow training and elevating speeds (even in power-operated triple mounts), excessive vibration and muzzle flash, and the fact that the ammunition feed was via a 15-round fixed magazine which necessitated ceasing fire every time the ammo had to be changed. According to "US Naval Technical Mission to Japan report O-47(N)-2", all magazines had to be loaded by hand as no specialized loading equipment was ever developed. Overall, it was more comparable to the U.S. 20mm Oerlikon, though vastly inferior to the U.S. 40mm Bofors in every respect except rate of fire (and only barely in that respect: the Bofors could put out a sustained 120 round/minute because of its constant-fire top-fed ammo clip design; whereas the 25mm's frequent ammo box changes lowered its nominal rate of fire to only half of its theoretical maximum of 260 rounds / minute).
The Japanese ranked in order of seriousness the problems with the gun as:
1. Elevation and traverse was too slow, even with powered mounts
2. The sights were ineffective against high speed targets
3. Firing the multiple mounts caused excessive vibration which reduced accuracy and prevented effective target tracking
4. Too little ammunition in each magazine resulted in a low overall rate of fire (the gun used 15 round self-contained magazines).
In Rapid Fire, Anthony Williams writes that the intermediate calibre weapons (including the US Navy's 1.1"/75 caliber gun") were relatively unsuccessful during World War II, the mounts were much heavier and more complex, but the shells lacked the range and hitting power of the larger 37 and 40 millimeter mounts. Certainly the Japanese ranked increasing the caliber of autocannons as the number one priority of research and development.
This weapon in particular was recovered from the GabGab beach fortifications and installed in front of the barracks on display for guided tours.
What type of artillery is this?: Anti-Aircraft/Anti-Tank
Where is this artillery located?: Military Grounds
What military of the world used this device?: Japan
Date artillery was in use: 07/28/1945
Cost?: 0.00 (listed in local currency)
Artillery is no longer operational: yes
Still may work: no
Are there any geocaches at this location?:
No
Date artillery was placed on display: Not listed
Parking location to view this Waymark: Not Listed
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