Garmin or ballistic app is wrong?

[Remington92]

I’m getting my rifle fine dialed for hunting season and left scratching my head comparing my Garmin xero to what ab mobile is giving me for dope. My rifle is a tikka ss 6.5prc chopped to 22” with a scythe on the end of it and I’m running factory 143eldx precision hunter. My Garmin gives me an average of about 2850 and the box says 2960 which jives with the shorter and slower tikka barrel. Out to 400yds my adjustments are dead on. Next target I reached out to is 800 yds and to get ab mobile to give me the correct elevation I had to slow down to 2780 or an extra 0.3 mil. I’m at 3200ft da for reference.

Is the garmin that far off or is there something goofy with what ab is feeding me? Also anyone ever have issues that you have to reload ab a couple times to get consistent values

 

[Wrench]

What your group size, wind, DA, DOF, BC....and have you tall targeted the rifle?

 

[Macintosh]

If your adjustment values are off a little that would do that—tall target should tell you.
Are all of your inputs correct? DA mainly, but also sight height, etc will affect it some.
BC is also going to be off—did you use a litz drag curve, or?

Fwiw Ive been starting with box velocity and using the ab truing function using all three distances, and it does work to get good dope from near to far…without a chrono I have nothing to compare it to though. Maybe thats a benefit?

 

[Remington92]

Group size today was just under 8” at 800yds. Not sure what tall targeting is but I did hang a piece of cardboard bout 3’ wide by 4’ tall with a target in the middle which is how I got my low impacts at 800. I checked DA populating on the app against my kestrel and that was good. Level open prairie without a stitch of wind today. I used the g7 bc that pre populated for the 143eldx in ab mobile. Double checked sight height as well. 1.5” with T084 rings is what I got.