I have one on a Leupold 6.5 x 20, 1000yrd turret set to my hand loads, they ask for avg. temp, avg. elev., BC of bullet and velocity. I hunt from 2000-8000' elev. in -20 - 60deg above. I had them set it at 3500' @ 35deg with my bullet specs., for the most part it's pretty **** close, 100-200yrds right on, 300-500 a little high(about 2-3"), 600-800 yards back on and haven't shot a lot much further. Once you start hitting 700 and past given temps and elevations can really start messing with you more than anything!