The three I use: 1: Up to mule deer-.25-06 in a H&R Handirifle with a Redfield scope 2: Up to moose/elk-.308 in a Ruger GSR open sights. 3: Up to anything on the continent-.338 RCM in a Ruger M77 Hawkeye open sights
If I had to, I could get away with only the .308, if I had to pick two to cover everything I’d take the .338 and either of the other two, with the .25-06 being better for antelope and whitetail at longer ranges.