KD 5.56 ammo; 55g or 62g ?

[maxwell]

Did you have a crono to verify velocity?

Yes:

I used chrono data and a ballistic calculator to predict my comeup for 400 yards, and ended up 16" high on the target.

[Lomshek]

Sorry I missed that.  No idea why it would be that far then off unless the BC was way off or some other input was incorrect.  I'd dig deeper into the inputs and settings on the ballistic calculator.

Edited to add this -
I wonder if the click values on your A2 were different than the entered values?  Like you said it's academic now just surprising that it was as far off as you observed.

I've used Strelok Pro for a while with velocity readings from my Caldwell (Midway USA) crono for handloaded single fed 80 grain Sierra Match Kings and been pretty much dead on out to 900 yards for drop.  The errors I've observed have been from the shortcomings of my cheap scope's ability to dial accurately (or me to count the mushy clicks).

Here's a 5 round group fired prone slung up from my 16" Daniel Defense at 900 yards with a 1-4x Burris MTAC.


Strelok predicted 32.3 MOA so I dialed 28.5 MOA on my scope and used the second aiming dot.  That put me a smidge higher than ideal on target. 

Here's a screen shot of what that looked like with my reticle in Strelok.


The group is opening up (I think) because the rounds are going transonic at about 850 yards.  Under 800 yards they stay about MOA'ish and are pretty much dead on for predicted elevation.

The big white circle is a 24" dot simulating the target gong at a shooting match I was prepping for.