RE: .243 for whitetails
Now this is just my opinion, and I will not offer it to be combative.
But my experience with Whitetail hunting, and I have more than 30 years of experience and well over 100 kills, is that if you are going to hunt whitetails, you want to have the best possible combination.
No one gun is good for everything. No one bullet is good for everything.
It would be the same as your personal private automobile. You would not take a Corvette deer hunting and you wouldn't want to drive a new Silverado 160 mph with BFG Mud terrain tires either!
Even though some Corvette's have more than 350 Hp - new from the factory, the same as a new fully decked out Silverado.
But just because they both have similar motors, transmissions and large tires - doesn't mean that they can perform the same task the same way.
So comparing a .270 Winchester to a .243 Winchester is not comparing apples to apples. More like comparing apples to potatoes.
The further NORTH you go, the bigger a deer gets. So someone from South Carolina - giving advice to a hunter from Maine just won't cut it either. They are hunting the same kind of deer, just that a deer from South Carolina might be 1/4th the size as one from Maine.
Yes, some inexperienced people should stick to smaller calibers, especially if that hunter is small and not very good with a center fire weapon.
But I am 6'3 / 270 lbs and can shoot in just about any position.
I would not want to generalize a hunter into one group or another, but here is my two cents.
A person from the city will not think twice about spending $100 on a good dinner in a fancy restaurant or going out to see a show - as long as the other half has a good time, money is no object. But when the same man tries to talk to the other half about spending $500 - $1000 on a good deer-hunting rifle, all sense of logic goes out the window.