Your disclosing of this speaks volumes of your integrity. From my years of collecting Winchesters, my sheer speculation is that I doubt that will a factor in serviceability and little effect on pricing. Straight grain walnut such as Winchester used on these rifles, is not uncommon to develop such hairline cracks. Seldom develops into serious yielding of the stock.
We need more Gun Traders with your level of honesty. I applaud you. .Good luck with the sale.
Last edited by oneoneshot; 02/03/19. Reason: correction
