I've used the .257 Ackley and it's a decent round. In later years, I found that if I wanted a little stronger medicine than the .257 Roberts, I simply defaulted to the .25-'06.
During the last ten years that I was able to hunt, I used the standard .25-'06 with 100-grain bullets quite a lot and I never found it lacking ... even for bull elk. And for antelope & mules/whitetail, the .25-'06 is absolutely superb.
In retrospect, I was way too slow to appreciate the .25-'06.
Blessings,
Steve
