. 308?
Go for a 4-16x
Everyone has there own opinion but a number of people say 24x is too much, I'll track down the terminology but basically for ranges that you'll be shooting a 308 it's too close and causes distortion or some ####. Others will say 50x is good to go.
I found a 6-24 looked dumb on a 20" which was what pushed me towards the 16x (along with the feedback from competition shooters about ir)