nchawkeye
Something else that some deer hunters can't understand...Hit a deer in the lungs with a 7mm Mag bullet that is designed for elk and he will run farther than that same deer hit with a .243 100gr bullet...Simply because most of the energy of the 7mm Mag ends up in the dirt on the other side of the deer,but most of the energy from the .243 is expended in the deer...
For the most part I disagree with your evaluation even your round ball evaluation.... In niether one of your statements did you include "range" and or Xwinds - range is the great equallizer. Your round ball gun would be marginal out here in the west and the open spaces. Sure there are shots of 50 yards or less, probably lots of them but there is also a great chance of a big shot over 100 yards in a clearcut or across a draw.
In your estimation of the 243 vs the 7mm - I disagree because even as the 7mm does usually pass through (which I prefer)in a hurry and still has a lot of energy going away from the deer... the hydrosatatic damage that the velocity & projectile weight of the 7mm can do far outweighs the 243. The 7mm will likely liquify theevery vital organ in the cavity. Granted at closer ranges the 243 will perform just fine on thin skinned deer, extend the range and the 243 will start to deminish.
I am also not saying that the 243 will not do the job, but the 7mm will do the job over a wider range of varibilities.... personally I would not use either one for deer - my choice would be a 270.
Just my personal opinion....