Man, I hate these kinds of posts...You guys either have some dang tough deer, can't shoot or can't track, not trying to insult anyone, but I can find no fault with a .243 and whitetails....I guess guys want a 5-6 inch diameter hole in the other side of the deer, but the .243 with any of several factory bullets is plenty...
I own one centerfire rifle, a .243 Ruger M-77 that I bought new in 1980...I have killed at least 150 deer with this gun and have never lost a one...I just can't imagine what you guys find wrong with it...We kill 40-50 deer a year on our farms in eastern NC, my brothers own 270s, 7mm-08s, .280s and cousins/buddies/nieces/nephews, etc own several other cartridges, frankly we don't see any difference in how far one deer runs over another, whether hit by a .270 or a .243....Hit them with a broadside center lung shot and the deer runs 25-75 yards...Hit them with a high shoulder shot (bullet through both shoulder blades and spine) and the deer drops....Hit them in the guts and you are in for a long night in the swamps...
If your gun will group Hornady 100gr InterLokts, 100 gr Remington CoreLokts, the Federal Premium 100 gr Nosler, 100 gr Sierra GameKing or the 85gr HPBT you will have no problems...