Well, I'm one of the lucky ones. A couple weeks ago while out shooting I noticed something was amiss between my ballistic app and actual field data. At 455 yards my ballistic app gave me 2.0 mils but actual mils needed were 1.8 1.8/2.0 = 0.90 At 910 yards my ballistic app gave me 6.1 mils but actual mils needed were 5.49 5.49/6.1 = 0.90 So I have a 10% error in my scopes tracking. I went into the app and changed the elevation and windage correction factor to 0.9. Hopefully this will correct the problem for my hunt. It's my fault for not checking the tracking on the scope first. After my hunt I will run a box test and a tall target test before I send it off to Vortex. A really nice guy on Long Range Hunting forums who runs a ballistic software company checked all my data and set me up with a custom ballistic chart for my hunt. Many thanks to him for his help.