I might depend on how serious your looking to shoot and do you still hunt with the same rifle. Also the target target you shoot at can help groups size. I have a nice custom hunting rifle and use a old 3.8-12 scope. It will shoot some very small 400 yards groups on a target like this- http://www.about-shooting.com/images...-in_target.png
I can't expect to shoot well at a simple black dot at long range any more
Would it change just for a target / match use. You bet ya. 24 to 32 power.