Another vote for the .243.
I've killed some 20+ whitetails with Mr. Sierra's 85-grain HPBT--and it's loaded by Federal as well as by me. Fed does good; I get as good a group with theirs as with mine, at around 3/4 MOA.
I killed some 25 or 30 prairie dogs, last Tuesday, with the little 55-grain ballistic tips. Those do horrible things to prairie dogs.
Art