Japanese use of the Model 89 grenade discharger as a low-angle
direct-fire weapon has been definitely indicated, according to recent
reports. To use the weapon in this manner, the piece must be
emplaced at an angle about 15° from the horizontal. With the Model
89 shell, direct laying at ranges of 50 to 100 vards has been reported
as effective. However, this shell has a contact fuze, and premature
explosions will occur if trees or other obstructions are in the line
The fragmentation hand grenade Model 91, adapted for use in the
discharger, can also be used for direct fire at ranges up to 60 yards.
Principal advantage of the hand grenade is its time fuze (6 to 7
seconds) which will not detonate if it passes through light
obstructions, thus allowing its use from behind foliage.
For maintaining an angle of 45° in firing the discharger, the
attachment described below is used.
This consists of a small drum, approximately 1.15 inches in
diameter, mounted of a circular clamp which fits around the base of
the barrel. The attachment is oriented by means of a red sighting
line on the back of the clamp, which should be aligned with the
sighting line on the barrel.
The drum has a small transparent window on the lower rear side,
a red line in the center of the window. When the grenade discharger
is held so that a luminous line inside the drum is aligned with the red
line on the window, the axis of the bore forms an angle of
approximately 45° with the horizontal.