Lancaster, I measured the base of both pieces of brass the Norma brass is 11.87 and the resized Winchester brass that I necked up is 11.85. Like I said in my original post the 9.3x57 Norma brass which has not been sized will chamber but the resized 8x57 brass will not the only difference I can see is the slope of the shoulder. This gun has been rechambered and the barrel is stamped 8,7 then 57 below that. This is the same rifle that I posted pics of in this section of the forum. Thank you for your response though because I never considered the base. I was working on the thought that the 8x57,9x57,and 9.3x57 had the same dimensions with the exception of the neck and shoulder.