We have shot a lot from ewes, to big rams...shoot further forward with an adequate caliber. We have have 2 rifles for guys here to shoot one is a 6.5 creedmoor and the other is a 270 win. I have shot them with 22 creedmoor, 22-250, 243, 6 ARC, 6 creed, 25-06, 257 wby (a lot), 6.5 creed, 6.5 grendel, 270, various 30s, and 338s.
I'd say anything with 120 grain bullet going 2700 fps will do. Any of the new stuff with a fast moving heavy "big" BC bullet will hammer them and buck the wind. If I go out to really kill the biggest ram I can... I like 338 Norma or my light 338 RCM--bucks the wind well hits great with plenty of speed. Plus my gun is set up to peg anything inside 800...where I'm at--wind is always an issue.