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"Japanese Rifle Grenade Launcher, Model 100" from Tactical and Technical Trends

The following intelligence report on the Model 100 (1940) Japanese grenade launcher was originally published in Tactical and Technical Trends, No. 47, June 1, 1944.

[DISCLAIMER: The following text is taken from the U.S. War Department publication Tactical and Technical Trends. As with all wartime intelligence information, data may be incomplete or inaccurate. No attempt has been made to update or correct the text. Any views or opinions expressed do not necessarily represent those of the website.]


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.

[Japanese Rifle Grenade Launcher, Model 100]

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 99132 yards
6.5-mm Model 38, long102 yards
6.5-mm Model 38, medium111 yards
6.5-mm Model 38, short117 yards


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