I think the stamping, K.P.P.B. VII No. 82. indicates that this pistol was assigned to the Prussian Police(Schutzpolizei), or more specifically, it was pistol number 82 of the Kriminalpolizei(detective force) at the Bonn police school in the Potsdam district.
To break this down by marking,
The first letter "K" indicates that the pistol was Assigned to Kriminalpolizei(detective force).
The second letter "P" indicates "Potsdam district".
The next two letters "PB" go together and indicate Bonn police school.
As of this writing, I do not know what the V II indicates.
At the end, the "No. 82" indicates item number 82.


