I used a 2 x 7 Leupold for years on my 25-06 with a duplex cross hairs. I set up targets that were 18" tall between top and bottom. Built a paint frame to paint out the target with a 2" cross in it. Measured out 300, 400, and 500 yd set up. Used my scope at 7 powder to see how that 18" measured up at those ranges. That became my range finer. I could look through the scope and what the yards was or about what it was. Use the either the crosshairs dead center or raised the crosshair up to the top of back for 400yds, and point of bottom post at top of back for 500yds. My group would be about 3" below the top of back at those holds at the different yardages. That was my range finer and it was deadly. Very quick too.