Over about ten years I patiently experimented with how to maintain and slightly improve the stocks on older German air rifles.
I did not want a 50 year old gun showing normal wear to have a refinished stock if it retained most of it;s original finish. My goal was for it to look normal for it's age . Most were finished by spraying them with a nitrocellulose lacquer, no fine finish but suitable. I had many guns with feathered edges, lacquer peeling or worn away, lots of dents and gouges. I would lightly sand the edges with fine fine grit till buttery smooth, I rarely steamed out dents, they are normal on that age gun. I tried JM London oil, lots of others, most too fine for the original gun. I finally cut Tru-Oil with thinner and let it soak in then over weeks kept applying and buffing until I could match the lacquer. With practice I got where I could save and match the finish to where it looked original but was careful to make it not new looking. Frank Korn, Frakor, is a master stock restorer, look at his guns.