My daughter has shot 20 deer and antelope with the .257 Roberts (basically a little less of the same flavor) and I've probably killed that many or more with it, and my ex shot 13. We have had great success with 100 grain core lockd and 120gr partitions. That 120gr partition is going to be tough to beat unless you are seeking a high BC.
Come to think of it, the old non +P 117gr RNSP at 2600fps killed everything we hit with it, even out to 300 yards.