243 for deer is just fine. 243 for moose is just a poor idea. There are so many better choices, they would be hard to count.... and that is only the lower recoil rounds.
Comparing an 243cal 85gr TSX against a 30 cal 180gr CL, in the hand of a kid without great deal of experience, etc., simply does not hold water in large game hunting.

Imagine your grave on a windy winter night. You've been dead for 70 years.
It's been 50 since a visitor last paused at your tombstone.....
Now explain why you're in a pissy mood today.