Pretty difficult to lighten a Mauser action itself, without impinging upon it's strength. going to a perferated mag box, along with pot-metal bottom metal or plastic, would be the only strength saveing methods I'd use. I really don't mind packing an 8 1/2 to 10 pound rifle (inc. scope), so I don't lighten anything.

A lighter action for an 8x57 would be a model 94 or 96.