.22 LR nuff said.
6X45 or 47 just because the .223 isn't legal in Colorado for big game and possibly some other states I might hunt. With 55-70 grain bullets it plays hell on varmints as well. 80-100 grain for deer and pronghorn.
.270 Win for everything else and just because I like it.
.375 Ruger or H&H for if I ever want to hunt DG in Africa.