Minenwerfer Z.s.u.m. 25 second fuze

[Darkman]

My mate Ron has this WW1 Minenwerfer Zsum fuze. It's missing the gaine/booster but is still very nice.
He has a reference book "Notes on German Fuzes and Typical French and Belgian Fuzes, 1918" that shows such a fuze and indicates it has a 21 second maximum time. Ron's fuze appears identical but is 25 seconds. Were there different marks of this fuze?
Any information appreciated.
Cheers, Graeme

 

[lcn]

Hi Graeme,
I join an extract of the document on the German fuzes in 1918 (GQG Armes du nord et de l'Est 1 - 2 Bureau) .
It is stated that there were two ranges 7-21 and 7-25 sec without specifying whether it is a different model.
Cordialement Jean Paul