The Japanese Army, which has relied heavily upon the trench mortar for fire
support, has developed a 150-mm mortar.
Called a "medium" mortar by the Japanese, this Model 97
(1937) 150-mm weapon is a conventional smooth-bore, muzzle-loading,
bipod-mounted mortar of sturdy construction. Captured
on Peleliu Island, this weapon is the largest Japanese
mortar yet found. There it was emplaced in a concrete pit with
the muzzle level with the top of the pit.
This 150-mm mortar, which resembles in design the standard U.S. 81-mm mortar,
weighs 770 pounds complete with sight, and fires a conventional type of
high-explosive shell weighing approximately 57 pounds.
The weapon is sighted by means of a 3-power panoramic elbow telescope, and the
Japanese claim it will throw a projectile a maximum 2,187 yards. Bursting radius
of the shell is reported to be 65 feet, with some fragments thrown 100 feet further.
For transport, the mortar--including the sight--breaks down into these five component
|Tube|| . . . . . ||257 pounds|
|Base Plate|| . . . . . ||337 pounds|
|Bipod and elevating gear|| . . . . . ||100 pounds|
|Traversing gear, shock-absorbers, and mortar clamps || . . . . . ||74.5 pounds|
|Sight|| . . . . . || 1.5 pounds|
The tube is 75.37 inches long and has a reinforcing muzzle band, while the
heavy, ribbed-steel base plate measures 47.75 inches by 35.5 inches.
|The Japanese Model 97 150-mm mortar, largest enemy weapon of
this type yet encountered by U.S. troops in the Pacific.|
|The 150-mm mortar shell weighs approximately 57 pounds. The
bursting radius is reported to be 65 feet.|
The weapon is assembled, adjusted for fire, and operated like
the U.S. 81-mm mortar. However, the firing mechanism resembles that of the Japanese
Model 99 81-mm mortar, using a firing-pin cam shaft built into the base-cap, rather
than a fixed firing pin.
The Japanese are known to have another Model 97 150-mm mortar, which has not yet
been encountered. It is reported to weigh 1,540 pounds and to have a maximum range
of 3,828 yards. There is a possibility that this mortar may be installed on a