You have to ?true? the ballistics program.

In StrelokPro, you input the data (cartridge/rifle) and it will give you an estimate. You then have to shoot at certain distances and adjust your data in the program for it to start putting out reliable data.
For instance, I use StrelokPro. After I build a gun in the program, I shoot it at 400/800/1,200 yards and correct or adjust the program. After that, it?s pretty darn spot on or within 1/10 or 2/10 Mil on every distance out to subsonic.

Do you know how to true the program? There is an icon you select that takes you to the page where you adjust your actual hold from the recommended one. Once you do that, and save the data, the program reworks the ballistics algorithm to give you better data.

I use StrelokPro and Applied Ballistics programs. They are pretty good tools.