Everything I have shot with the 156gr berger hasn't taken a step - 5 whitetails and 2 coyotes, ranges from 110yards to 383 yards. BUT I am running them at 3,156 fps in a 264 win mag. I would not personally shoot a 6.5 creedmoor at an elk, with any bullet.
I would suggest shooting a 270 win or 30-06 and even putting a muzzle break on there to help with recoil. My 115lb wife shoots a 6.5 lb 30-06 with no issues.
If the 6.5 creedmoor is all you have to work with, I'd go with a barnes bullet to ensure it held together and penetrated deep - the 120gr or 130gr ttsx would work great and you would be able to run them a little faster as well.