Many years ago, it was first mentioned in writing (of a book) I believe in Jone's book if I remember correctly. So since it was many years ago, it is hard to pin down. Further Spandau was actually a repair facility for the military, but not a manufacturer, that is why there is doubt about Spandau marked guns. It makes sense that they might have "repaired" them, but why bwould they have "made" them?
Possibly other collectors with more experience can give some further information?
Ed
Possibly other collectors with more experience can give some further information?
Ed