RD I am pretty sure that M70's used the same contours for standard and magnum chamberings, things like FW's and 375 H&H's excepted.
Do you think that the factories want to, in general, maintain a certain shank diameter and shank length for say magnum rounds that are based on H&H rounds and perhaps this is why mag contoured barrels are heavier than non-magnum chambered rounds ? Maybe I wasn't stating my observations clearly enough as I don't believe RinB has responded to my question.
