R.Marshall,
This is an often seen type rifle made in Zella Mehlis and sold to many dealers in finished condition and gunsmiths for finishing in their own style. Edgar Hubner's address is Suhl and is shown as a Buechsenmachermeister, so it is highly possible that he finished it. If he did finish it, it would have likely been proofed is Suhl. If you post photos of all the markings, including proof marks( found under the barrel) additional information can be provided.
Mike