Thanks for all of your replies and the warm welcome! My No.1 was made in the early 90's it is not a Pre Warning model so I dont think it is collectable. I was wondering about the twist rate for each cartridge, are they the same? I think I read somewhere that ruger used a 1/14 twist in the 458 Win. Mag. but I could be wrong, does anyone know? Also, who would be a good gunsmith in the U.S.A. to do this work? Would I have to change extractors? I would think so but not sure. Thanks!