Charlie, you certainly CAN make 8X57mm cases from .30/' 06 brass. First trim them to about 58 or 59mm O/A length. Expand the necks to 8mm, then use an 8X57mm full-length die to size them. Adjust your die by screwing it into the press' s die station a little at a time, setting the shoulder back JUST to the point that the the rifle bolt will close with the application of just a little force. This indicates that your case' s shoulder is contacting the shoulder of the chamber. You next trim the cases to 2.240" , and load them with a starting load. Upon firing, the case will fireform to your chamber, and have a slightly sharper shoulder than the .30/' 06 has.