I shot a cow elk in western WY with a 7x57 using a 175 grain factory load. I can't remember if it was FED, REM, or WIN ammo. Broke the near side shoulder with the first shot and killed it with a second shot through the neck. I have very limited elk hunting experience, but for me the most important part of punching an elk tag has been to anchor it by breaking one or both shoulders so that you can put a follow up shot into its vital organs. I've watched more than one elk shot through the lungs go a couple hundred yards before it died of blood loss and they always seem to run into less accessible places and make the recovery that much more challenging.
Based on one event that required two bullets, I'd opine that the 7x57 is an adequate elk cartridge if the shooter is competent and the bullet is properly constructed. I couldn't have asked for a better outcome from a common cup and core bullet.
