What causes ballistic app errors

[Ryeguy]

While shooting today I shot out to 550 & 650yrds and to get on target I had to subtract 2moa off each yardage call. That's all I had time and ammo for but curious if anyone knew what would cause this? Yes I'm pretty sure all my info is correct. Between 2 apps, 4dof and Eagle ballistics they had but the same call.
Shooting 338 NM. 300 gn Bergers 2840fps.
650 call was 12.15. I got on target at 10.
This a scope issue? Any help appreciated. I know i need to start working back from 100 and see exactly where it falls off but didn't have time today.
Edit: BC and 100 yrs zero was off a bit. Might have it figured out

 

[ShtrRdy]

I was going to suggest thec100 yard zero was off. That would cause a constant error for all distances.

If you haven't done so yet, it's a good idea to do a tall target test to see if your scope has any tracking error, or perhaps I should say how much tracking error your scope has.

 

[lancetkenyon]

"Garbage in, garbage out".

Sounds like you figured it out.

 

[yobuck]

Thats just the way life goes friend.
But i would write that down, and next time maybe start there instead of where you did.

 

[JAYgs8163]

User and data input errors cause incorrect ballistic app calls/output.

 

[lupis]

It's a wonderful life when things work.. not so much otherwise.. I did a tall target test.. found my scopes were tracking high… took awhile to figure out how to adjust in the app, but all is well now.. old dogs can learn new tricks!