A U.S. intelligence report on Japanese Model 100 grenade launchers, from the Intelligence Bulletin, December 1944. [Editor's Note: The following article is wartime information on enemy weapons and tactics published for Allied soldiers. More accurate data on Japanese weapons and tactics is available in postwar publications.]

 

MODEL 100 GRENADE LAUNCHER PRODUCED IN TWO TYPES Investigation has revealed that there are two types of the Japanese Model 100 (1940) grenade launcher. One is for the 6.5-mm Model 38 (1905) rifle and carbine; the other is for the 7.7-mm Model 99 (1939) rifle. Both launchers are remarkably similar, and both are intended to fire the smooth-sided Model 99 hand grenade, Type A (first found on Kiska Island and now generally known as the "Kiska grenade"). They also can be used on the U.S. carbine M1. A Japanese manual says that the purpose of the launchers is to provide a means of projecting the Model 99 grenade, Type A, further than it can be thrown by hand. The launchers, which are fitted to rifles and carbines after bayonets have been fixed, are intended for use in close combat. While it is believed that the launchers can be used interchangeably on either the Model 38 or Model 99 rifles, and on the Model 38 carbine, the Japanese have introduced certain differences between the two models of launcher, to permit quick identification. The thickness of the bullet escape-tube wall is greater in the launcher for the 7.7-mm Model 99 rifle, and the diameter of the interior of the tube for the Model 99 is 9.7-mm instead of 8.5-mm. Exterior features facilitating recognition include the locking pin. The launcher for the 6.5-mm Model 38 rifle and carbine has a triangular locking-pin ring, and the pin is introduced from the operator's left side. The launcher for the 7.7-mm Model 99 rifle has a circular locking-pin ring, and the locking pin is pushed in from the right. Probably the most obvious difference is that the vertical sighting line on the back of the launcher for the 7.7-mm Model 99 rifle is not found on the launcher for the Model 38 6.5-mm rifle and carbine. Figure 8. These are the two types of the Model 100 (1940) grenade launcher. At the left is the launcher for the 6.5-mm Model 38 (1905) rifle and carbine. At the right is the launcher for the 7.7-mm Model 99 (1939) rifle. It should be noted that the launchers are attached only when bayonets have been fixed. First, the locking clamp is attached to the muzzle of the rifle or carbine. A Model 100 launcher is then slid over the locking clamp, with the cup upward and the bullet-escape tube in front of the rifle muzzle. When the launcher is in place, the spring clamp holds it to the rifle. The locking pin is pushed in so that it passes behind the rear of the bayonet handguard, and automatically locks the launcher in place. The cleaning rod need not be removed. Figure 9. This drawing shows the Model 100 (1940) grenade launcher in position. This is the type for the Model 99 (1939) rifle. A Model 99 grenade, Type A, is illustrated here. To fire, the butt of the rifle is placed on the ground after a live round of ball ammunition has been placed in the chamber of the rifle and a grenade loaded. The grenade itself is placed cap downward in the tube after the safety pin through the cap has been removed. Since the fuze of the grenade takes only a short time to burn, the barrel must not be elevated more than 40 degrees in the case of rifles, or 30 degrees in the case of the 6.6-mm Model 38 carbine. Greater elevation will result in an air burst. When the rifle is fired, the bullet passes out the muzzle into the escape tube. While the bullet is passing through the escape tube, gas from the cartridge flows up into the grenade discharger cup and expels the grenade. Ranges are as follows: 6.5-mm M38 (1905) rifle (at 40 degrees elevation)—82 yards 6.5-mm M38 (1905) carbine (at 30 degrees)—109 yards 7.7-mm M99 (1939) rifle (at 40 degrees)—104 yards. The grenades turn end over end in flight, both grenade and smoke from the fuze being visible. Air bursts over 10 feet high are believed to result in very little injury. On the ground, the danger area appears to be about 5 yards. The grenade will explode in the sea, sending up a 20-foot column of water. It is important that the bullet-escape tube be kept free of dirt and rust. The Japanese warn against using the rifle for ordinary fire while the launcher is attached.

Back to Articles by Subject | Intel Bulletin by Issue | T&TT by Issue | Home Page