That patch on the stock is where the original sling was attached.
The stock has been "sporterized". Originally it would have had a full stock like a regular K98.
I have one similar that was made by Simpson.
Some of these could have been "bring backs" but most in this country were imported post-war and sold as sporting rifles.
Here's a shot of mine and a shot of an unaltered Simpson example.
Your Walther originally looked similar, with the full stock.
Imho, these "sportmodells" are about the finest example of a single-shot .22 rifle as you'll find.
