The 7x57 should have zero problems feeding from the same action as the 9.3x62. Give Ray Atkinson a ring at Atkinson hunting adventures. He will set you strait. If you intend to handload, he can give good advice about how to have the throats of both barrels set up for best performance as well. However, both rounds do just fine with decent factory loads in standard chambers. Your GM might not like the idea of long throated (i.e. Non spec) chambers anyway.