So keep it simple man.. like the chart says- sight in 2.5 inches high at 100yds, shoot it at 300 and 400 to see where it hits, if your scope has the 200, 300, 400, marks, then you may be closer to the drop marks by just going 1.5-2" high (actual 200yds zero). Out past 250 or so you can just aim dead center and shoot, but if a long shot presents itself...Those marks are great as long as you try them and see how they are for your gun and your ammo.. even if you try it and discover that your gun hits 4" low using that mark at 400.. then if you know the range you know where to hold without dialing anything, and that is nice to have.