No. 12 Fuze with Unusual Markings

[Depotman]

My No. 12D Mk X fuze looks as if its been converted and the stampings changed by the addition of a small, upper case "F" between the "No. 12" and the "D". I have an Ian Hogg list of EIGHTEEN different versions of the No. 12 fuze, but his No. 12 FD is described as a No. 12 F, converted to a No. 12 FD. Obviously not mine!. I have also looked at the relevant 'List of Changes' and the conversion from a No, 12 D is not described.
Has anyone got any further information? Depotman

 

[TimG]

@Depotman
Trevor,
If it was a conversion, I would expect an asterisk to follow the mark and the initial manufacturer and lot number barred out.
Do you know if the 12FD Mk X and the 12D Mk X shared the same delay time?
You could always claim it's a No. 12 F Mk 510!

TimG

D denotes Delay
F denotes spring strength is one fifth of standard item.

 

[Depotman]

Thanks Tim,

I'm assembling the relevant Lists of Changes to come up with a definitive answer - hopefully!
I'll post soon!
Depotman