The area where Oberndorf is stamped looks different too doesn't it? It's stamped on a narrow bar, Waffenfabrik is faintly stamped above.
The grips have "29" stamped in the back so it could mean gun #9.
The grips have the horizontal lines, very faint.
Someone went to the trouble of making a branding iron so I think it would've been applied to more than one gun.
It was a complete gun with very loose grips when I got it. I took it apart to see what I had and was so disappointed that I wrapped it in a rag and tucked it away. Somehow the rest became separated from the frame and I can't figure out for the life of me where I squirreled it away. So I've no idea what it's chambered for.