303mike, just out of curiosity, why do you think Winchester came out with the 375win if it is identical to the 38-55? Just for marketing? The way i understand it is they are indeed two different cartridges, maybe very very close in dimensions but different all the same. I know that the 375win cases are thicker in the web and case head, as well as different bullet diameters, albeit very close. Im a firm believer in Murphy's Law so i will use 375win brass in my Marlin but i dont doubt your knowledge....
