Well what intrigued me most is the barrel (and so little to compare it to); the serial fonts suggest the barrel and receiver are original mating's, but the barrel coding is usually front of rearsight (typical of the Berlin firms mid-late war, Hannover is not near Berlin but these are product off-shoot of their rationalization efforts late n the war); though these are so difficult to find anywhere near original who the hell knows what is "normal" - many survivors are interwar reworks and little more than bastardized barrel-receivers (coupled with the fact these are more related to the sterngewehr than first line production)
Ihad piddled with trying to connect the C/K acceptance to a maker, most probably WMO/18 barrel, probably salvaged to Hannover for this purpose, but that is a guess, - WMO, Spandau & DWM are connected at the hip, so to WOK. Anyway getting late and past my bedtime!