For hunting in the mountains I'd go with a bolt gun. There is no reason to hump around a 12lbs 308.
How are we suddenly talking about mountains? While I agree with a bolt if you're humping over elevation, the OP said nothing about mountains.
I am looking at 308 for a possible moose/elk rifle
Because you don't see a lot of moose and elk in the Kansas fields, Texas plains or Georgia woods:
Thanks for making my point with pretty pictures.