I used thi when I set up my 6.5-06. I had to make a lot of corrections to the sight height and bc to get it to be accurate beyond 700 or so, but I finally tweaked it to actually follow my path to 1400yds. do not think if you plug in the numbers on your box and a sight height that you can be a 1k yd marksman. it took me several days and lots of rounds to verify my map.