IIRC winchester started using color on ammo boxes in 1936 or 1937 then stopped using color during WWII(remember "Lucky strike green has gone to war?) but I suspect that winchester didn't load a lot of .30-40 full patch for civilians, so the early mid thirties is a good bet.
Well, it a 30/40 Krag which was used with ole Teddy and the rough riders in Cuba. After the 30/06 came out it took over that U.S. 30 cal. description so those could be 1898-1906 circa.
I'm no expert but if I were betting I would guess that.