When the Americans captured the Guadalcanal airfield, they
found that the Japanese had left behind three types of
antiaircraft guns. These were naval guns, set up on shore. They
included twelve 75-mm antiaircraft guns, one 25-mm pom-pom, and
one 13.2-mm machine gun. The 75-mm weapons, on naval-type mounts, were
emplaced in a triangular formation, each side about 4,500 yards in
length. The pom-pom and the machine gun were found in separate
positions along the shore.
2. DETAILS OF 75-MM A/A GUN
The 75's (see fig. 1) were in three batteries, each consisting of
four guns. They were emplaced in open pits with sandbag revetments, and
had 360-degree traverse and 75-degree elevation.
Each gun has two telescopic sights, one mounted on each side of the mount
with a traversing handwheel on the right and an elevating handwheel on
the left of the mount. Lateral deflection, vertical deflection, slant
range, and super elevation are all set on a series of drums, disks,
and dials on the left side of the mount.
The slant-range drum has two scales. The outer is graduated from 0 to 7,000, and
the inner from 100 (opposite the 0 on the outer scale) to 300 (opposite
6,000 on the outer scale). This drum is turned by a small handwheel.
The lateral-deflection drum turns on a spiral, and is graduated from 0 to 200.
|Figure 1.—Japanese 75-mm A/A gun.|
The superelevation curves are on a disk, operated by another small handwheel.
The gun also has an open sight mounted on a drum. The controlling
handwheel moves only the vertical sight.
There were no directors at any of the gun sites, but at each was
a navy-type coincidence range finder with a 68-inch base.
The guns fire high-explosive shells which have 30-second mechanical
time delay and percussion fuzes. The weapons have no fuze setters, as
ours have. Instead of fuze setters the Japs used a manual two-piece
tool. One piece, a long plier-like tool, holds the fuze by its bottom
ring, below the graduations. The other piece, shaped like a truncated
cone with handles on each side, fits over the fuze nose and engages
the lug on the side of the fuze. The fuze is set by holding it with
the first tool and rotating the second tool. It is not clear how the
fuze-setting is obtained.
3. DETAILS OF 25-MM POM-POM
This gun is a Hotchkiss type, gas-operated, air-cooled, magazine-fed
weapon (see fig. 2). It consists of three 25-mm cannon mounted side
by side on a naval-type, three-gun pedestal mount. The gun fires
armor-piercing and tracer shells from a 15- or 20-round vertical
box magazine, which fits into the top plate of the receiver. The
sighting is on the same general principles as that of the 75-mm gun
|Figure 2.—Japanese 25-mm pom-pom gun.|
4. DETAILS OF 13.2-MM MACHINE GUN
This weapon is a 13.2-mm (52-caliber) Hotchkiss type, gas-operated,
air-cooled, magazine-fed antiaircraft machine gun, mounted on a
naval-type pedestal mount. It is fed by a 30-round semicircular
magazine which fits into the top of the receiver. The gun has a
shoulder stock and pistol grip. Antiaircraft sights are mounted
on the gun. They are composed of a front-ring antiaircraft sight
and a rear sight: the latter consists of a small vertical rod
with a ball tip. This weapon is the standard heavy antiaircraft