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. 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.
Mountings 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. Guns in twin mounts were in individual cradles and could elevate separately. All twin gun mounts weighed approximately . 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. The
Type A single mount could depress −7° and elevate to +75°, but the
Type B reduced the maximum elevation to 55°. Both mounts weighed approximately . The
Type A was fitted on the
Hatsuharu class and the
Type B on the
Shiratsuyu-class destroyers.
Ammunition 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 and a maximum range of . A new, heavier, but more streamlined, high-explosive projectile with a range of was under development when the war ended. ==See also==