Gotta agree with
Wrangler John.....all of my rat rifles wear Lupy 6.5-20X's, and I usually spend most of the day shooting ground squirrels (or PD's) with the scope set on 14X - 16X. Sometimes in the early morning before the sun gets high in the sky and the mirage is not an issue, I'll use 20X, but you really can't use powers much in excess of 20X in the field for more than just the first couple of hours of sunlight. (Based on 40+ years of field experience shooting the little buggers......) Besides, if you can hit ground squirrels peeking out their burrows and make head shots on them using 14X or 16X out to 300 - 350 yards, do you really need more weight/bulk or magnification? Not me.
If you want to pay for all that magnification, know that you'll seldom use it in the field just because of atmospheric conditons that seem to always prevail where varmints live. Of course if you want to peep on neighboring galaxys, well then get all the magnification you can.
