The real question nowadays is: what does the 243 do better than a tight-twisted 223
The answer is simply, plenty. If there wasn't more lethality in a larger bullet going faster, guides in Alaska and PH in Africa wouldn't have minimum caliber restrictions...
For deer hunting, with what I've seen, I cannot tell the difference between the wound channel of the 223 and 243. Other than as Ingwe noted, how far away one round holds its velocity makes a difference.
I do not think that there is enough difference between 22 and 24 calibers to know the difference other than velocity.
