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The No.247 found it's use on the following British grenades:
No.69 , No.70 , No.73 , No.77 , No.79 , No.82 and it was also fitted to the SOE (Experimental) General Purpose grenade.

An earlier version of the impact-mechanism was used on the
No.54 grenade.
An almost exact copy of this mechanism was in use as an aireal bomb fuze; "Tail Fuze No.854".

Description (ww2 manual text) :

This fuze is designed to operate when thrown in any position, it is therefore known as the "Allways" Fuze.
The body and cover are made from moulded plastic. A lead antimony inertia pellet carrying the detonator (1.7 grn "A") has a central channel to take the steel striker. The striker is held away from the detonator by a spring and also by a safety belt which passes through the striker above the inertia pellet.
The safety belt is secured to a tape and weight, which are wound clockwise around the body of the fuze.
The striker head is a hollow platform and on it rests a lead alloy ball.

Action (ww2 manual text) :

Before throwing the grenade, the cover is removed, thus exposing the tape and weight.
On throwing, the tape will unwind from the fuze and pull out the safety belt, leaving the striker supported above the detonator only by the spring.
On striking the target in any position, the fuze will operate; either by:
The inertia pellet riding forwards onto the striker or by the movement of the ball pushing down the striker onto the detonator.


There are some different marks with some small modifications.
They are the following:

-Mk1A , "A" stands for brass inertia pellet
-Mk1Z , "Z" stands for zinc alloy inertia pellet


Variations :

THE ORIGINAL DESIGN "Mk1" was made for the
No69 and No73 grenades. These fuzes are the ones that have the small snout on the base.
Its striker has a machinally split tip, which makes it a shared point.

FIRST MODIFICATION was removal of the snout to make the fuze suitable for the
No77 WP smoke grenade. (still fits the 69 and 73)

SECOND MODIFICATION was a change to "B" filling in the detonator, in combination with 1inch length of quickmatch which was inserted in the flash hole of the fuze body. This variation was for the
No79 HC smoke grenade only. Safetycaps for these were painted green.

THIRTH MODIFICATION was the use of a shorthened arming tape. This modification was in use only for the No.82 (Gammon) grenade. The No82 was used a lot against vehicles, and as they were thrown from short distances, the arming tape needed to be shorter. 4½ inch tape , instead of the normal 11½ inch. Safetycaps for these were painted red.

-Mk2 ,

has a different designed striker which penetrated the detonator with just a simple short single point .

The internal of the lead-antimony inertia pellet has been altered.
Instead of the 1.2gr "A " primer, a 1.7gr "A" primer was used.

-Mk3 ,

As production of No.247 fuzes gave some difficulties, a new design of the fuze body was chosen.
In its outer form nothing changed, but instead of the screw-in top, it now had a screw-in base.
This made it easier to fit the internal components and made manufacturing safer as well.
Drawing on the right thanks to Allan.

Same fuze was also produced in Holland by "Artillerie Inrichtingen" for Dutch service on the Dutch made No69 grenade.
Other countries too?

Photos below © Paul Spence.


Another variation used during and after WW2 is the one on the No.69 DRILL version.
Click on the link to see it.


Here's a small collection of different markings that I found on the caps, I guess there are many more.


Above: the cap marked "KMI" is a modern reproduction, not real bakelite but plastic made.

The two caps with the red paint © M. Jochoms.