That will be one handy rifle...as for why 20? Seems like a 20" win mag is going to be a fair bit faster than a 20" 30/06 or 308 right? Efficiency? Sometimes light and fast handling with plenty of wallop at 800 is maximum efficiency. Been thinking of a 22 incher myself. Climb an alder choked slide with a 20 and a 26, see what ya bring next time