The new Model 100 (1940) Japanese grenade launcher, has been test-fired
by an Ordnance intelligence unit and found to have a maximum range of 132 yards.
This grenade launcher is believed to be designed for use on the Japanese 7.7-mm
Model 99 rifle. However, it can also be used on all other Japanese rifles. The
launcher has the advantage of using only standard ammunition, and no special
ammunition is required. The projectile used is the small Model 99 (1939) grenade. The
grenade is propelled by the powder gases from ordinary ball ammunition.
The accompanying sketch shows the Model 100 grenade launcher attached to the
rifle, and with its ammunition. The launcher weighs 1 pound 9 ounces and consists
primarily of a small tube and a large tube mounted side by side.
The Model 99 grenade is placed in the large tube with the safety pin removed.
The gun is aimed, and elevated at the proper angle, and a round of ball ammunition
is fired. As the bullet passes through the small tube, the tube is blocked, and the
expanding powder gases pass into the large tube through a by-pass, ejecting the
grenade. The force of setback arms the grenade, and it explodes 4 to 5 seconds
after leaving the launcher.
The wing nut, which can be seen in the pictures, operates the closure to a
small gas port, which is probably used for adjusting ranges. The rifle can be fired
from the shoulder when using this launcher. When this launcher is used, the
report of the rifle is slightly muffled. The grenade is plainly visible in flight, and
it leaves a trail of smoke behind it.
On preliminary firing tests the range at 30 degrees elevation was found to
be greater than the range at 45 degrees. The ranges at 30 degrees were as follows:
|Type of Rifle|| ||Range|
|7.7-mm Model 99||132 yards|
|6.5-mm Model 38, long||102 yards|
|6.5-mm Model 38, medium||111 yards|
|6.5-mm Model 38, short||117 yards|