Last night I went through all of my Winchester reference books. According to Ned Schwing's book, Winchester began using lacquer during WWI as a stock finish. There are cetainly those more knowledgeable than me but I believe this to be an error. According to my research nitrocellulose lacquer was not invented until the 1920s. Its original use was for the automobile industry. I believe that it is more likely that Winchester began using lacquer during the 1930s at the earliest and was certainly using it after WWII.
Some authors state that Winchester used a combination of linseed oil and tung oil as their "oil" finish. Other authors state that Winchester used just linseed oil. There are so many differences of opinion amoung the various authors of Winchester books that it is difficult to know who is correct.
