RE: .243 for deer
I guess that because I bow hunt alot I have the sametendencies with bullet placement as arrow placement for the most part. Other then the head and neck shots with a gun, I dont shoot deer with a rifle anywhere I wouldnt shoot them with a bow. So that may be why I dont have a prob with the smaller calibers/guns on deer(I dont shoot enough large game animals to comment on anything but deer).
I still cant see a larger caliber letting me shoot a deer anywhere I wouldnt with a smaller gun. Unless your just talking about maybe a running deer and a plain bad shot even then Im not sure if a bad shot is any better with the big gun.
Im not saying your wrong Im just making sure I understand what you mean.