Yep. 6.5 Creedmore if you’re starting from scratch. .308 (7.62X51) if you’re like me and already have reloading supplies for .308
I’ve never got into long distance shooting but I do have a few calibers that do it quite well. I like fast movers so none of mine will handle the longer heavier bullets available but they do OK for hunting here in West Texas’
I shoot 150’s in my 300 Weatherby, 140’s in my 7-mag, 130’s in my 270 WSM and 100’s in my 257 Weatherby. They’re solid 500 yard rifles, with the proper bullet and twist you can stretch them out to twice that range. 500 yards is about my limit, I’ve only taken two animals past that and both were with the 300 Weatherby. One was a bull Elk in Colorado and the other an Aoudad ram down by Big Bend. Buddy of mine builds long distance rifles and his personal rifle is a 300 Weatherby shooting a 230 grain Berger. He’s taken that rifle well past 1000 yards.