257 wby
You didn't say what make of rifle, some are a lot easier than others. Rem the most difficult, ruger, winch, sako, 98 all pretty easy. 26" bbl preferred.
The 257 wby is a truly outstanding cartridge, you won't be sorry. With the new powders it really shines (RL 25) Forget all the barrel burning hyperbole and have fun with the flattest shooting, least recoil gun out there. When you burn that barrel out you can put on another and go have fun for another 5000 rounds. I have owned several and never burnt a barrel out yet, never been my only rifle though. Killed a cariboo at over 400 mtrs 1 shot through both front shoulders. Current one is a 700 CDL stainless fluted and punches 110 accubonds into 1/2" as long as I do my part, I love my 257Wby !!!!