Today finally I found some time to have a look into my copy of the Knirim book.
Here it is what I found there:
1. First of all, in the whole thick brick of a book, Laco is mentioned just two (2) times --
and both occasions are related to the B-Uhr.
Quite disappointing, right?
Especially when you compare the number of mentionings
of Lange (33), Wempe (15), IWC (10), and Stowa (7).
2. Some info regarding the W-SS whatch:
-- the "M-B" mark on the dial shoud indeed be interpreted as "Messbatterie".
In fact, the watch is described as
"Beobachtungsuhr fuer Messbatterie mit Anhaltevorrichtung fuer die Unruh"
-- Supposedy it was produced by Wempe and Laco for the missile test facility at Peenemuende
(where at that time Sturmbannführer SS Werner von Braun was developing
the missiles known as V-1 and V-2).
-- Interestingly, the watch has the specification number (Anforderungs Nr.) Fl. 23883
identical to that of the B-Uhr of the Luftwaffe.
Other interesting features include:
- giant size of 65 mm
- 1/5 second marks on the dial
- mirrored numerals for minutes
[edit: typo corrected]