Vol423,
The proofmarks don't show the nominal caliber(later they did), rather they show actual measurements.The marks on your rifle are consistent with 6.5X57R,just as you said. It is perfectly fine to buy factory ammo and use those cases, but after reading your postings over the years, I'm a little surprised you are ready to give up now.With enough work and equipment,we can make considerably smaller cases than 6.5x57R from 7x57R. I don't have Norma 7x57R cases( the RWS,DWM, and Z&B cases I do have may be different),otherwise I would try to work out a way to use the cases you have.Tenn. and East Al. are not that far apart, if you come down here one day, with the rifle, cases and dies, we can work it out.On reflection,I remember the headsize of 9.3x74R is usually slightly smaller than 6.5x57R, so forcing a 7x57R case into a 9.3x74R sizing die(all the way to the rim)and driving it out with a punch, may work. I don't remember whether you have the 9.3 die or not.I would offer to trade 6.5x57R cases for 7x57R cases,but I have more of that caliber than I need for right now. By the way,the 6.5x57R is more than worth the trouble,mine is great and you will think the same of yours.
Mike