I have hunted elk many times with a 270 and always done just fine. In fact every elk I ever shot with a 270 fell to one shot except one I killed with 2 shots at about 400 yards with a 270 Short Mag, and when I dressed it out I found the 2nd shot with my Benelli Auto-loader was actually not needed.
Most elk I have shot just fell at the shot, and some have gone about 10-15 feet and then fell down. But I can't say I have seen any difference in how fast my elk have fallen comparing my 270s to 30-06s, 7MM mags, 300 mags and even my 338 mag.
And I mean absolutely none at all.
Others may say different, but that's what I have seen in over 50 years of killing elk, and seeing others kill many elk too.
