In Brophy's book "L.C. Smith Shotguns on page 8, it gives the following from a May 15, 1935 paper going into detail on the making of the 3 highest grade "elsies", Monogram, Premier and DeLuxe. Saying that they are all custom built, the stock wood is all imported, and "the stocks are finished with as many coats of oil as are necessary to completly fill the pores and obtain the perfect finish."
The finish on the other models wasn't as labor intensive as the top grade, but still nice, and varnish was used on the stocks and as well on the receiver.
If you look up Tru Oil, you will see that it is a varnish.
