The new 6.5 japanese brass made by Prvi Partizan (nny), distributed by graf and sons, is marked as 6.5x51R, I just went to the basement and checked. People are reading into it too much. Why extreme caution is always stressed in reloading some get carried away. Other countries do not necessarily have to conform to SAAMI specs, and may not differentiate between rimmed and semi rimmed. Different stated measurements for the same cartridge is known. 2 others that come to mind are 7.65x53 belgian and 7.65x54 argentine. Also 7.62x54R russian and 7.62x53R finnish. This may not make sense here, but that is what makes america great.