It is almost not even worth considering. I've never even thought about the length of the barrels that my hunters bring. Usually I spend more time worrying if they'll be able to see the elk and shoot the elk without a bench rest and a week to get it done.
My younger teenage daughter has killed two elk with 20'' barrels on 308s.
I used to have a rem ltr in 308 with a 20'' tube. That thing was very accurate and easy to kill with, including elk.
