I do not know the situation in Germany, but in Japan an american officer could purchase "surplus" American rifles from local depot. I have a Remington 03 with the papers showing sale to an AF Captain for the grand total of $20.00.
This officer then had the rifle sporterized by a local Japanese"gunsmith" who did a credible job of building a stock, removing the rear sight sleeve, and adding an open sight mounted to the barrel by a dovetail.
Sight, buttplate, etc were all US made obtained from the local PBX.
I bought the rifle from the Captain in about 1967 for the same $20.00. He told me that what he did was fairly common then.
I suspect the rifle shown here had somewhat of a similiar history.