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"New Japanese Weapons" from Intelligence Bulletin, November 1943

[Intelligence Bulletin Cover]   The following is a report on new Japanese weapons encountered in the Pacific, from the November 1943 issue of the U.S. Intelligence Bulletin.

[DISCLAIMER: The following text is taken from the U.S. War Department Intelligence Bulletin publication. 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.]




Several new types of Japanese weapons are described in recent reports from observers in combat areas of the Pacific. These weapons include:

a. A hand grenade which is actuated by a pull-type igniter;

b. A small, smooth-surfaced hand grenade which is actuated by striking the fuze against a hard surface—as in the case of the Model 91 and the Model 97 grenades;1

c. A 47-mm antitank gun which is completely modern in design; and

d. Four types of booby traps.


a. Description

This grenade, which has an over-all length of 3 3/4 inches and a diameter of 2 inches, is easily distinguished from Models 91 and 97 because it has no lengthwise grooves. The weapon has five traverse grooves, however, and it also has a lead cover which is grooved to provide a grip for the fingers in removing the cover. On one side of this grenade, fitted to the top and bottom, are two rings. These could be used for carrying the weapon, or for anchoring in case it is used as a booby trap.

b. Table of Characteristics

Over-all length   _ _ _ _ _   3 3/4 inches.
Length of body   _ _ _ _ _   2 3/4 inches.
Length of cover   _ _ _ _ _   1 inch.
Diameter of body   _ _ _ _ _   2 inches.
Diameter of cover   _ _ _ _ _   1 1/8 inch.
Body (material)   _ _ _ _ _   Cast iron.
Cover (material)   _ _ _ _ _   Lead.
Weight (total)   _ _ _ _ _   449 grams.
Weight of filler   _ _ _ _ _   39.5 grams.
Weight of body   _ _ _ _ _   509.5 grams.
Loading factor   _ _ _ _ _   8.7 percent.
Filler   _ _ _ _ _   Granular TNT.

c. Operation

To remove the lead cover, depress the cover thumb release on the side of the grenade (see fig. 4). The cover then screws off in 1 1/2 turns. This exposes the firing string. When the firing string is pulled, it draws a friction igniter between two pieces of match composition and fires them. The match composition, in turn, fires a 5 1/2-second delay train, which fires the detonator, thus setting off the main charge.

[Figure 4. Japanese Pull-type Hand Grenade.]
Figure 4.—Japanese Pull-type Hand Grenade.

d. Booby-trapping Possibilities

Since this grenade can be activated by a pull on the firing string, it is better adapted to booby-trapping purposes than the Model 91 and the Model 97 grenades....


a. Description

This grenade is small in comparison with the Model 91 and Model 97 Japanese grenades (see fig. 6). It is 3.5 inches long and 1.75 inches in diameter, and weighs approximately 10 ounces. Because of its light weight, the grenade can be thrown almost as far as a baseball. This fact indicates that the weapon is designed primarily for use in offensive operations. It is called "offensive" hand grenade in this section because its model number is not known.

[Figure 6. Japanese Offensive Hand Grenade.]
Figure 6.—Japanese Offensive Hand Grenade.

The body of the grenade is smooth and cylindrical, both inside and outside, and has a rim at each end. Its nonserrated body is an additional help in distinguishing the weapon from the other types of Japanese hand grenades. It is closed by a threaded plug, which has a hole in the center to receive a threaded fuze.

The workmanship of the grenade is good, and ordnance experts consider the fuze an improvement over that of the Model 91 and Model 97 grenades.

b. Operation

A sleeve that holds the firing pin and the firing-pin retainer spring in place is held to the fuze by means of a small screw. The detonator booster is crimped to the lower part of the fuze body. The safety pin, which prevents the firing pin from striking the primer, is held in place by a cord. To arm the grenade, remove the safety pin and strike the head of the weapon against some hard object, such as a helmet. Thus the operation is like that of the Model 91 and 97 grenades.

4. MODEL 1 (1941) 47-MM AT GUN

This new Japanese weapon is a split-trail piece of modern design (see fig. 7). Its silhouette is low, and its tread is unusually wide. Because of these features, plus the fact that the wheels are fitted with pneumatic tires, it is evident that the piece is adapted for towing by a motor vehicle.

[Figure 7. Japanese Model 1 (1941) 47-mm AT Gun.]
Figure 7.—Japanese Model 1 (1941) 47-mm AT Gun.

The barrel of this weapon is extremely long, and is heavily reinforced at the muzzle. This indicates a high muzzle velocity. The trails, also unusually long, are equipped with a locking yoke and handles. The wide tread and small wheels permit a wide traverse. A wide shield, cut away at the bottom, is provided.

A complete check has not been made on the ammunition used for this weapon. However, the armor-piercing round is 15.5 inches long and weighs 6 pounds 5 ounces, complete. The case, made of brass, is unusually large and long, and is necked down to take the 47-mm projectile. The projectile has a red tip, a black body, and a white band just in front of the copper rotating band....

1 Intelligence Bulletin, Vol. II, No. 1, included a section devoted to these and other grenades and mines which have booby-trapping possibilities.

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