Very nice Sam, very tough to find this original and matching... probably not even a handful of similar rifles, most were used up thoroughly. Wish I could find the origin for these, still not convinced Hannover is a match, perhaps though, it was important and an AK HQ, but I could never tie a munitions depot or artillery depot to the place, which seems to be where most collection centers and reworking was done. I could even see a fortress or some training grounds being one, there is evidence of such after WWI, but nothing seems to connect Hannover other than its an important city that starts with an H that had some military functions (and away from the unrest late in the war - which would exclude cities like Hamburg, that place had runaway riots 1917-1923 rivaling Berlin....)
Anyway, neat rifle and neat BC/C-RC, which as you say is pretty uncommon, only Erfurt seems to have been prone to this inspection problem, though I could see Simson pulling a few too... not sure if Simson had a real problem with quality/production or just some antisemitism at work (which Germany was no special case until Hitler came along... contrary to modern "historians", Germany wasn't special in that regard, matter of fact they weren't the worse, antisemitism was widespread throughout all of Europe and the US, naturally it was worse where Jews were more common and more successful in the professions... Russia/Poland had it worse, France was just as bad as the worse spots in Germany, and Austria had a terrible problem in Vienna where Jews were extremely successful in the professions and academia, - England too was no haven for Jews, anti-immigration laws from Eastern Europe was focused upon Russian Jews fleeing pogroms, and Austria's problems were from her ridiculous "Empire")