Well, I haven't killed a ton of antelope, but the farthest I've shot one is 286 yards, which is well within the effective range of a .257 Roberts, one of my favorite cartridges. My wife shoots one with excellent results. I've shot antelope with a variety of cartridges from .22-250 (not legal in WY) to .300 WSM. All worked and made the antelope equally dead. Now I hunt them nearly exclusively with my 13" barreled .30-30 AI Contender. I think antelope get too much credit as a long range species. Rare is the day you can't sneak within 300 yards of an antelope. I shot two of my three antelope last year in WY with my pistol. The buck was about about 80 yards and a doe was at 145. The other I shot with my 6.5x55 at about 150. The wife shot all of hers with the .257 Roberts.
All that said, if I wanted to hunt only with a rifle, and set it only for antelope, I would probably get a lighter weight 25-06 and stoke it with a good 100ish bullet (maybe the 110 Interbond) and be happy. The .257 Wby would be nice, but brass is expensive and they require a longer barrel to get the best performance. In a standard 24 incher, the .25-06 will do nearly as much with less powder.