on target shooter nz: WWI Jam Tin Grenades:

Sunday, 25 February 2018

WWI Jam Tin Grenades:

Colonel L Jackson developed the "Jam Tin Grenade" early in the First World War - as an alternative to the unsatisfactory No.1 Percussion Grenade.

No. 1 Grenade With 'Streamers'

- Impact Grenade Sometimes Struck The Rear Trench Walls

& Detonated When Being Thrown.

If you look carefully above .. the boys are throwing 'Jam Tin Grenades' with the 'Leach' catapult:

The No. 8 grenade consisted of an inner tin which held an amount of Ammonal explosive, inside a larger tin with the void being filled by 4 layers of shrapnel balls separated by cast iron rings. Inside the ammonal was a standard No. 8 Mark VII detonator with a length of Bickford fuse protruding from the top of the grenade fitted with a Nobel percussion igniter. This double wall design is why the official name for the original Jam Tin grenade was the "Double Cylinder Hand Grenade".

The 'Roburite' on the label is an interesting "flamefree" mining explosive that was safer to use in "gassy" coalmines where 'firedamp' & fine coal dust were present. (The Nobel 'percussion igniter' is used here fixed to a length of fuse cord - the internal spring-loaded firing pin detonates a percussion cap that lights the fuse when the 'rip-cord' is pulled .. then you throw it.)

However - supply couldn't keep up with demand so the Royal Engineers put-out a set of instructions that enabled troops to build their own versions from expedient supplies.

The need for this design mostly ended as the Mills Bomb was made available to the British Expeditionary Forces (B.E.F) .. But the Commonwealth ANZAC troops in Gallipoli were held to be of a lower priority "a Side Show" for supply - so were left to make a variety of their own improvised war materials in 'factories' down on the landing beach - where at one stage more than 50 men were producing 200 bombs a day..