Have found this thread very interesting. Thanks to all.
Whilst I have only recently managed to fill a long held desire with the purchase of a 257RobImp, I also have been thinking of a 257WM. For my part I think the 25 to 26 cal range are pretty well spot on for the bulk of Auatralian hunting needs. As such I was thinking of building a 257WM on a Ruger No1B in 25-06 and just having the chamber re-cut. The Ruger comes with a 26" bbl already and it would be a cheaper option than building up a rifle from scratch.

Interesting tip re: the 7mm Rem Mag cases.