Japanese WWI Grenade and WWII Sling Grenade



WWI Impact Grenade

TYPE- Fragmentation

WEIGHT- 600 gm





FILLING- 35 gm


This grenade was used by the Japanese in WW I.  The main body is a rough cast steel cylinder with an open bottom and a stem cast on the top end.  A groove is cast into the body around the bottom end.  The explosive cartridge fits into the body from the bottom end.  The bottom is closed by a turned wooden base piece.  The base piece is covered by a cloth tube which is then tied of at the top end in the groove formed in the main body.  The bottom is also tied off at the bottom end in a groove formed in the bottom end of the wooden base piece.  The cloth and lashings also act to hold the wooden base piece in place.  The remainder of the cloth tube forms a tail to ensure the grenade flies head first.  The top end of the body has a stem that is drilled through in the centre.  The impact igniter mechanism fits into the central hole.  A detonator set is inserted through the centre hole into the main charge.  A wooden plug with a small hole in the centre is then inserted in the hole and pushed down to hold the detonator set in place.  A safety block fits around the stem.  The striker assembly consists of a cap, striker, and rubber plug.  The striker is mounted solidly in centre of the cap.  The rubber plug has a hole in the centre that fits tightly over the striker.  The rubber plug is inserted on top of the wooden plug and the striker then inserted in the hole and pushed down until the cap rests on top of the safety. 

 The grenade is normally issued unprimed with the detonator sets separated from the grenades.  For use the detonator set is inserted into the body through the stem, the wooden plug inserted, the rubber plug inserted and finally the striker assembly inserted.  To throw the grenade, remove the safety block.  At this point the grenade is very dangerous and the thrower must ensure that the head of the grenade does not come into contact with anything.  The grenade is thrown at the target either by holding it by the body with the tail facing rear or by grasping the tail and throwing it using the tail as a handle.  When thrown, the tail trailing behind the grenade ensures it travels headfirst and strikes the ground headfirst.  When the grenade hits, the striker assembly is driven down into the body until the striker hits a percussion cap in the igniter set.  When hit, the percussion cap flashes into the detonator causing it to fire.  The exploding detonator sets off the main explosive filling.

Japanese WWI grenade                



Sling Grenade


TYPE- Fragmentation

WEIGHT- 1 lb. 3 oz.

DIAMETER-  1.84 in.

LENGTH- 5.8 in.             

IGNITER- Matchead

FUZE DELAY-  4.5 sec.




This grenade was identified during WWII and simply identified by Allied forces as a “Sling Grenade” due to the method of throwing.  In fact it seems to be a modified version of the WWI grenade perhaps using stocks of the WWI grenade held in storage since then.  It appears that the modifications are quite simple fixes that allowed the use of an obsolete and dangerous grenade to be used with much more safety to the user.

 The modifications consist of removing the cloth tail while leaving the cloth portion that is lashed onto the grenade to assist in holding it together.  A hole is drilled through the stem on the bottom of the wooden base piece and a metal ring fitted into the hole.  A cord is tied onto the ring.  The impact igniter is replaced by a friction ignited type.  The igniter consists of a brass tube containing a detonator, delay element and match head.  This igniter is inserted into the body of the grenade and held in place by a wooden tube that holds the igniter tightly and fits tightly into the hole in the head of the body.  A wooden ring with a flattened side fits over the stem at the head of the grenade.  The flat portion of the ring has an abrasive surface.  The head of the grenade is then closed by a sheet metal safety cap that is taped on.

 For use, the tape is pulled off and the safety cap removed.  Care must be taken to retain the wooden ring.  When ready to throw, the abrasive surface on the wooden ring is scratched over the match head igniter which causes it to ignite and light the delay element.  The grenade must be immediately thrown either by holding it by the body and throwing it in the normal manner, or grasping the cord attached to the base and throwing it like a sling.  Greater range can be obtained using it like a sling but accuracy likely suffered as a result.  Once the delay element is ignited it will burn down to the detonator in 4-5 seconds.

Sling grenade