lancaster,
That is exactly correct, because the base diameter of the 6.5x55 is larger than that of the 6.5x57R and the chambering reamer will not clean up the existing short chamber. I have already turned these barrels to a super-lightweight profile and also faced 1/2" off the breech end. I will have loadimg dies and a finishing reamer in my hands on Thursday afternoon. Brass is impossible to find right now but I have about 50 once-fired 8x57JR brass from my Cape gun which I intend to neck down to form into 6.5x57 brass.