Its great for deer, maybe the best out there, but it's also; in a professional guide of @25yrs words "the elk woundinest sum bitch ever made."
If a person can't kill an elk with a .270 then he can't kill it with a .338 either and he aint got no business hunting them. JMO too.
Just because a person has 5000 foot pounds of energy available to them does not mean that they need to go off taking risky shots. If that person can't put a bullet from a .270 where it needs to go then they sure aint gonna be able to do it with a 338 ultra mag and all the energy in the world aint gonna help them one bit. They will still end up tracking a wounded elk over miles of mountains.
I like this quote from Chuck Hawks web site.
Bullet placement is the most important factor in killing power. (Memorize that sentence!) I suspect that is why we hear such divergent views about many of the cartridges commonly used for elk hunting. The .270 Winchester, or any of the Category 2 cartridges, would be examples of this. Some hunters report that the .270 is a nearly ideal elk cartridge. Others consider it adequate, but not ideal. Still others consider the .270 worthless for elk hunting, and recommend nothing less than a .300 Magnum as the absolute minimum elk cartridge.
The truth is that most hunters simply have not shot enough elk, or observed enough elk killed, to be able to draw valid conclusions from their personal experience. It is very instructive to hang around the check out station for a controlled hunt--I have done this. There you can benefit from the experiences of lots of successful (and some not so successful) hunters.
Based on a fair amount of research, I regard the .270 as an adequate elk cartridge. If a hunter puts a decent 150 grain .277" bullet into a vital spot, the result is a dead elk. But the .270 will not bowl over even a relaxed elk. Neither, for that matter, will most other calibers. An elk is a big animal!
A lot of hunters are not particularly good shots, and a great many shooters flinch regularly with high intensity calibers like the .270 Winchester. So they think they placed the shot well, when actually they only wounded the animal. A .270 bullet will not bag an elk if it does not hit in an immediately vital spot. The elk may die later, but by that time it will probably be far away, and most hunters could not track an elk through the forest if their lives depended on it. These hunters are very apt to blame the rifle for their bad shooting.
The result is that guys who can shoot and who put their first bullet into an elk's vitals think the .270 is a perfectly adequate elk cartridge; those who can't and don't think it is lousy. They often conclude that nothing less than a .338 Magnum will stop an elk.
Of course, if you put a bullet in the paunch, a .338 Winchester Magnum probably does have a better chance of slowing down an elk than a .270--but you are not supposed to shoot any animal in the paunch in the first place! And even with a .338 a paunch hit can not be relied on to anchor an elk.