Because there are NO Spandau made lugers

There are fakes out there and maybe one or two that some experts believe has a real toggle, but Spandau, although they might have repaired lugers on a very limited basis, did not
manufacture any.
Also, the "Imperial" era ended in 1918 with the fall of the monarchy, then the Weimar period began (after a few false starts) which lasted until the official take over of Hitler in the early 1930's.
Ed