Here are some pictures of an RC German K98K that was captured in Vietnam and presented to a Sargent as a War Souvenir. The family did not have the bring back papers. I sold the rifle many years ago.
Looks like a Russian Capture, which makes sense, since that is most likely who supplied it to the VC! The condition of both rifles posted looks outstanding. Makes you wonder if they were captured from arms caches rather than in the field.