Schmidt & Habermann was a hot contender, but apparently their serial numbers would not quite have reached 366005 in 1939.
I may have posted the Bock-Paul Stadelmann connection previously, but a translation effort by Günter on a Bock article reminded me that Paul Stadelmann was an apprentice or employee at Otto Bock's concern. So when Paul Stadelmann made the transition to E. Schmidt & Habermann(co-owner) that would have greatly strengthened or established a sourcing line from Otto Bock to E. Schmidt & Habermann. I think the mechanic Paul Stadelmann to be a central figure and needs more study for post 1900 upper rung German sporting arms. Also wanted to rekindle interesting in Otto Bock's wares.
Kind Regards,
Raimey
rse
