10 cm/65 Type 98 naval gun

The 10 cm/65 Type 98 naval gun (六五口径九八式一〇糎高角砲), also known as the long 10cm high-angle gun (長10センチ高角砲), was a light caliber naval gun of the Imperial Japanese Navy used during World War II. It was employed on the aircraft carrier Taihō, the light cruiser Oyodo, and Akizuki-class destroyers. From 1945, land-based installations became more prioritized. The gun was considered by the Japanese to be their finest anti-aircraft artillery weapon. After the end of World War II, the gun remained in service on the two Japanese destroyers ceded to the Soviet Union and the Republic of China as war reparations.

The Allied forces first captured a shore-based twin-mounting of this weapon at Iwo Jima.

Description
The 10 cm 65 caliber Type 98 gun utilized a horizontal sliding breech, in addition to either monobloc (made from a single forging) or replaceable liner construction of the barrel. The gun featured a spring-powered rammer that was cocked by means of the recoil of the gun being fired; this allowed the rammer to load the gun at any elevation. 169 of the guns were completed, with 68 being land-based. One shortcoming of the gun was that it had a service life of only 350-400 effective full charges, as a result of the high muzzle velocity.

Mountings
These guns were used in twin gun turrets. The total weight of the mount and guns on Akizuki was 34500 kg. The mount installed on Akizuki could traverse at 12° to 16° per second and could elevate at a rate between 16° per second. It was electrohydraulically powered and could be moved by hand in the event of an emergency.

Ammunition
The gun fired a 13 kg high-explosive shell. Only nose-fused high-explosive ammunition was developed for the gun, and was of fixed type with a brass casing. This had a maximum range of 19500 m and a maximum ceiling of 13000 m at 90 degrees elevation, plus an effective range of 14000 m and effective ceiling of 11000 m.