As did Model 12's- Gene. from 1912 through 1954- the field grade forearms change in oal, diameter, and also the number of rings- post WW11 M12's (and other fine Winchesters) were stocked with lesser quality wood (except the Pigeon grades) and Custom Shop guns- due to all the walnut being used in America for military rifle buttstocks.

That may be one reason why I prefer M12's and M70's mfg. prior to 1940.

"The field is the touchstone of the man"..