RodB has researched and published information on the No 106 Fuze.

http://en.wikipedia.org/wiki/No._106_Fuze

He raised the following questions, which others here may be interested in :

1. I was surprised to find this did not appear to be a graze fuze, but really a super-sensitive D.A. (direct action) fuze. I.e. the only way to action the fuze was to push in the hammer projecting from the nose. There did not appear to be any internal inertia plunger or weights, balls, gizmos etc. typical of graze fuzes, which could activate the fuze merely on rapid deceleration or change of direction. This means that in theory the fuze would not detonate at all if it landed flat or tail-first for some reason, without the hammer coming into contact with anything, or just struck side-on. No. 100 and 101 were apparently true graze fuzes and would detonate no matter how they landed - but apparently the by-product of inertial activation was unavoidable slight delay, which No. 106 avoided.

Question : why didn't No. 106 retain some inertia activation (i.e. graze) capability in addition to the D.A. capability ? Would this have been too complex/expensive/heavy ? Or wasn't that really not necessary for its chosen mission, which appears to have been wire-cutting. Logically to me, if it was believed that the shell would always land nose-first, and hence always detonate, then No 101 was no longer needed as No. 106 would do everything, including demolition with simple addition of short delay. This was obviously not the case, and other graze fuzes continued to be used for demolition and general destruction.

Conclusion : D.A. was not a sure way of shell activation, and No. 106 would have been more potent with added graze capability. Why wasn't it given that ?

2.Ministry of Munitions History of 1922 mentions the development timeline and implementation of No. 106 Fuze, as approving its use from August 1916... and mentions all natures of artillery for which it could be used except 18 pounders. What I've found so far indicates that in fact the main users of this fuze were 18-pounders, together with 4.5 inch howitzers for short-medium range wire cutting, and 6-inch guns for long-range wire cutting. No 101 appears to have remained the main HE fuze for other uses.

Question : seems odd that the Ministry of Munitions history omits any reference to 18 pounders here. ??

3. This appears to have been a knock-off of a French fuze - does anybody know the background ?

4.The whole idea of having a feeler sticking out the front of a fuze waiting to come into contact with something is not rocket science. British troops were already getting slaughtered in front of barbed wire early in 1915 - why did it take until Jan 1917 to get a field gun/howitzer fuze (effectively just a No. 17 D.A. fuze with the needle on the end of a spindle sticking out an inch in front) into the field that could to some extent defeat barbed wire ?

Source: No. 106 Fuze