Portable Weapons

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Training Weapons

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Optical Weapons

Portable Weapons [Keitaiyou-Heiki]

Japanese infantry troops planned to move on foot. They did not think seriously of using vehicles, trains, and boats, so many Japanese weapons were designed to be carried by hand. Hand grenades, portable mortars, and grenade launchers fit into this category of weapons.

Grenades [Teryudan]

Hand grenades were used quite often in the Russo-Japanese War of 1904 -1905, but the first hand grenade officially was adopted in 1921 as the M-10. This grenade could be thrown by hand, but it also was designed to be discharged from 50mm M-10 grenade launchers. This grenade had a booster on the bottom to propel it from the launcher, and this grenade was developed to become the M-91 (1931) hand grenade. A Japanese soldier carried three hand grenades.

The M-97 Hand Grenade (1937)
The M-91 grenade made without the booster became the M-97 hand grenade, the most popular grenade used by Japan. The M-97 used 62g of TNT and it had a 4-5 second fuse.
The M-99 Hand Grenade
It appeared in 1939 with a body smaller than the M-97, and with a smooth exterior. This grenade used pcric acid explosive rather than TNT. The M-99 was encountered by Allied Forces initially on Aleutian island of Kiska, so it was called the " Kiska Grenade." An M-99 grenade could be thrown about 40m, whereas M-97 grenade could be thrown only to about 30m.
The M-98 Hand Grenade (with a wooden stick throwing handle)
t was made and sent to the China front.

M-10 production was about 100,000.
M-91 production was about 1 million; the M-91 was 125mm in length, 50mm in diameter, and it weighed 530g.
M-97 production was about 7.9 million; its length was 70mm, its diameter was 50mm, it weighed 450g.
M-98 production was about 100,000; its length was 200mm, its diameter was 50mm, and it weighed 300g.
M-99 production was 11million; its length was 90mm, its diameter was 45mm,and it weighed 300g.

New Findings

Portable Mortars [Tekidan-Tou]
Japanese troops often used portable mortars and grenade dischargers. There were two models of portable mortars and both could be used with signal projectiles.

The M-10 Grenade Discharger (1925)
It was often called a light (KEI) mortar. It discharged M-10 or M-91 grenades, which had boosters. M-10 was smoothbore and a spin upon the grenade being launched was created by six angled gas holes in the booster. The overall length of the M-10 was 525 mm, its barrel length was 240mm, its caliber was 50mm, and its weight was 2.6kg. When the M-10 was carried the support shaft with enclosed firing mechanism and the base plate were contained in the barrel of this discharger. Adjustment of range was effected by opening or closing a gas port in the base of the barrel.
The M-89 (1929)
It used special 50mm explosive shells five times as powerful as a hand grenade. This discharger had rifling and a copper band on the base of the projectile expanded upon firing to catch the rifling and to impart a spin on the projectile. Adjustment of range was made by the positioning of the shell in the barrel with a screw-jack mechanism in the support shaft which held the firing mechanism. The overall length of the M-89 was 60cm, its barrel length was 25cm, and its weight was 4.7kg.

The total production of the M-10 was about 7000 during 1925 -1937, and it was made by state arsenals and by Nambu. The total production of the M-89 was about 120,000, and it was made from 1932 - 1945 by Nambu Shimazu, Aisan, Riken, and Hikari-Seiki. The typical progress of a private manufacturer of weapons.

New Findings

Grenade Lauchers [Tekidan-Ki]

There were two or three models of simple rifle grenade or smoke grenade launchers which had been developed by 1930. The M-91 rifle grenade launcher was a simple tube type. In the WW II period two different models of rifle grenade launcher were developed and used; the M-100 and the M-2.

The M-100 (1940) rifle grenade launcher
M-100 7.7mm(Left) 6.5mm(Right)
It was made for launching the M-99 hand grenade. The launcher was attached to the muzzle of an infantry rifle and it consisted of a smoothbore pipe, which became an extension of the barrel, and a cup for the grenade located on top and aligned parallel to the pipe; when a standard ball cartridge was fired from the rifle, propellant gas behind the bullet was bled off into a gas port under the grenade which propelled it out of the cup and towards the target. Three types of this M-100 launcher were made - for the M-38 rifle, for the M-99 long rifle, and for the M-99 short rifle. The launcher was held to the rifle barrel by a clamp and fixture pin which used the bayonet hand guard. The grenade traveled 30m to 100m and hit a vehicle-size target quite easily. The range could be adjusted by varying the size of a gas port.

The M-2 Anti-tank Rifle Grenade Launcher
It was a German development transferred to Japan. It used a wooden bullet to shoot explosive projectiles of 30mm or of 40mm diameter. The cloth belt pouch used for this weapon contained the launcher, a takedown tool, a pad for the shooter's shoulder and a wood bulleted launching cartridge. A clamp with a screw handle was used to fix the launcher to the rifle's barrel. The launching pressure of the cartridge against the rear of the projectile was very great; this was called Tateki, and the shell was called Tate-Dan.