yessir, would be tough to get any "paper work" or documentation, short of the actual factory invoice ( delivery) lots of these were in use for training, and other purposes, and I recall manyyearsd agfo seeing a bunch of them come through ( released) that had short ,stubby barrels, threaded for silencers, and yes, had armory markings and stampings on them...we even had some of the barrels which, I recall it was from Stoegers or Bannermans, that they went ahead and removed the barrelsm, and rebarreled the guns, mix and match, could have a "Mark I" with a 4 3/4 inch "standard" barrel........military surplus baby....
some day I may try and get a hold of the one RST-4 we saw, that had "nazi" proof marks on the gun,,,,,that was a "winner" !!!!!