I did this last year with my Rem 600...found a 20" 700 barrel for $75 in 7mm-08 and had my gunsmith screw it on. I LOVE the results - accurate, light to carry and easy on the shoulder when you light it off.
I know it's not really a lot of difference, but I can feel the increase in kick comparing a 150gr .308 and a 140gr 7mm-08, and I'd take the 7mm-08 any day.
Besides, I believe a writer named Haviland and his boys have taken 20+ elk with their 20" barreled 7mm-08's.
