"But you can kill them with just about anything if you can put it in the right place."

This reminds me of the story Jack O'Connor used to tell about once on a sheep hunt in Yukon Territory when he and his party were being guided by some local Native American guides. When the inevitable debate started about which gun was best for whatever, he asked his guide. Guide said "Any gun good, shoot'um good!"

I believe this still applies! There is NO "BEST caliber"for anything, including elk hunting! I personally would not take a .243 or 6mm Rem. out elk hunting! But my daughter-in-law has used her .243 for elk for about 20 years, and none of her elk have yet had to be shot more than once.