RE: 243 and deer
I've shot a .243 before, and carried one hunting as a child, but never shot a deer with one.
I only know that there are a lot of people who love them and swear by them, and others who say they are under powered for some situations. Of course these are opinions that I've heard and I don't share either. I only mentioned it so that you could look into it for yourself if you so desire.
I do know this as a fact, since I'm looking at ballistic tables on the round in "shoot better II" while I type. This round is one of the flatest ones out there, so it has that going for it.