.243 is a fantastic round for anything up to and including mule deer with the right bullet (Nosler partition), but it is no flatter than a .30-06, and if I'm taking shots over 300 yds. at game animals, give me my .30-06 with a 165 gr. bullet. The .243 loses energy quickly past 250 yds. and the lighter bullet sheds velocity a little quicker. The .30-06, .243 and .308 are my 3 favortie rounds, I think the .243 is possibly the most versatile up to mule deer because of it's incredible varmint potential, mine groups 55 gr. BT's .5" at 100 yds and 400 fps, which is definitely in the .220 Swift category the "mother of all varmint cartridges". Don't take this post the wrong way, I love the .243, especially if you need a light kicking round, as long as the person that shoots it is proficient with it and practices often! It gave me my first three big game animal in one fall, whitetail doe, 4x5 muley buck, and a 15" antelope, a total of four shots, I missed my first on the doe!
Selmer