Both hunters, "both competent shots," aren't likely to butt-shoot an animal. That's the point I'm making. A bad shot is a bad shot, regardless of the cartridge used.

(edit) I use a .243 almost exclusively for deer and pronghorn. A friend once complained to me that he got rid of his .243 because it just didn't kill animals. He offered me what ammunition he had left. 75gr HPs. Varmint bullets. He truly didn't think there was a difference between 75gr HPs and 100gr PSPs. Another guy I know was shooting M80 military ball from his .308 for deer. The older I get, the more I shake my head at the choices people can make.

Merry Christmas!