Overall, both are adequate, and have killed countless deer and elk over the decades, although not the latest & fanciest cartridges.
The 30/06 will throw the 150-180 gr bullets fine for both species, as well as the 130-150 gr bullets for the 270. As with any cartridge, bullet selection (aka construction-type) for elk is important to hold-up for penetration. Less so for deer since they are thinned skin & less stout.
All cartridges have their range limitations, and being a good marksman to properly place the shot is paramount.
I've been a long-time 30/06 fan & user, and it's plenty to get the job done providing you know how to shoot within it's effective range, as is the .270.
Jack O'Connor was a big proponent and user of the .270 for many game species.
In 1955 legendary shooting editor Jack O'Connor wrote a column titled “Is the .270 better than the .30-06?” His answer, for the most part, was yes.
www.outdoorlife.com
Former Outdoor Life shooting editor Jack O'Connor was a legend in his own time who loved rifles, hunting, and writing about both.
www.outdoorlife.com
The ‘hot rod’ cartridge of the Roaring ’20s is as relevant today as it was during Prohibition
realtree.com
Contributor Bryce M. Towsley explains why his quest to find love for the .270 has gone unfulfilled.
www.americanhunter.org
These undeniably classic cartridges have been putting meat in the freezer and smiles on hunters faces for generations. Most of us have probably hunted with one or both of them at some point, but which is ultimately the better choice? Contributor Philip Massaro examines the pros and cons of each.
www.americanhunter.org
One of my favorite cartridges, and the one I’ve personally used more than any other in a lifetime of hunting, is the .270 Winchester. I was turned on to the cartridge by reading Jack O’Connor’s magazine articles and books. I grew up reading O’Connor’s prose when he was the Arms & Ammunition...
www.deeranddeerhunting.com
, so its the arrow 
