I didn’t start hunting big game with 6.5mm and 6mm until 2014. I always grabbed my .308 and .30-06 because that’s what I was taught.
I went up to Alaska and witnessed the old school locals killing moose, caribou, and huge bears with .223s and .243s. The next season I left the .308 and .30-06 at home and brought my 6.5x55 and .260 and .243 out for all my hunts. The story for me has been the same ever since for reason.
I’ve personally had better overall kill results in the last 10 years of big game hunting than I did the 18 years before that.