One of the best investments I've ever made was buying an 8MM-06 chamber reamer. A moderately warm handload in that case spanks any 8X57 I've ever seen, and brass is available by the truckload. 338-06 A-square loading data also works for the 8MM-06.
Jerry
At safe CIP level loads, the 8x57 gives up VERY little to the 8mm-06.