wartime Russian wood finish

[Sentryduty]

develop a colour of their own in use or to put it another way they wouldn't stay near white for long

Funny you mention it that way, many of the 1940-44 produced Soviet rifles I have stripped retain a dark discoloration around the end of the butt, areas the wrist and forearm grasping groove, in other words, where the rifle would contact the ground at rest, and where a soldier would place their dirty hands during use.

It does suggest the original finish was very not very durable or possibly uncoated prior to refurbishment.