Magnum is ok if you are going to spend the money and install a brake. My .300 win mag shoots like a .30-06 with a custom brake on it. Without a brake go with .30-06 or .270.
I've taken a bunch of pigs, deer, axis deer, five elk, two moose and a caribou with a . 30-06 and . 308. Both are great calibers and will get the job done on an elk.Thanks for the replies guys. I actually have a 30-06 back in Vermont I could bring out here, that would solve my issue. He could shoot the 308 or 06 and see what he likes.
I have cleanly killed 20 elk, numerous deer and moose with a pawnshop 30-06 I bought in 1996. My wife has killed 10+ elk, antelope, moose and bighorn sheep with her .270 without issues. Even a 30-06 has a lot of recoil for a novice shooter, don't go crazy with magnums! It is a cliché, but practice and knowing your limits are the key to making ethical, killing shots.I have been on 25 ish elk hunts with elk killed.
Bull Elk are tougher than you think.
Don’t even think about using a .243.
6.5 is too light.
.270 is marginal
7mag is much better
30-06 is good
.300 wsm and .300 mag and up are the right tools for the job.
You can kill an elk with any rifle and a perfectly placed shot, but you want a gun that can break the front shoulder and get deep in the lungs, or a gun that can anchor an elk when he gets buck fever and shoots it in the hind quarters.
The answer is the biggest gun he can he can shoot consistently.
And make sure he knows, you keep shooting and elk until it drops.