My furthest whitetail kill:
6BR, 105 Amax, 2850mv, 400 yds, LRF, double lunged broadside, golf ball sized exit, deer hit the ground after stumbling 20-25 yds, dead.
I'd happy punch any deer to 600 yds broadside thru lungs w/said AMax via an XC FWIW.
I love 6.5s, but concede if never shooting anything larger than deer/hogs, a 6XC WILL be a Top Contender in 8 twist of course.
A 243 will do as well, but the XC Brass like a 6x47 Lapua will not need the trimming over time and accuracy is BR grade.