Advanced Marksmanship 500m discrepancy

[silhouette]

I have 123gn Scenars going 2990 fps. My app data for all ranges up to 500m lines up with real world, but 500m tells me I need 2.6 mils and I routinely correct to 2.2 mils.
Is this human error?
I don't know what happens beyond that as this the extent of our range.
The 500m target is also on a 7 degree incline.

 

[whiskeysierra762]

Have you checked the tracking on your scope?

 

[silhouette]

No, I haven't.
Will do, thanks.

 

[Eric32]

What app are you using?

 

[Rudy Gonsior]

My questions would be:

1. How have you determined your velocity?
2. How have you determined your B.C.?
3. How have you determined your range
4. What ballistic solver are you using...and are all the imputes correct?

 

[Old Soldier]

Is this a one time try, or is it this way every time? One time means nothing. If it 2.2 mils every time, log it in your book, and go for it.

 

[phantomskittles]

You mentioned a 7 degree incline. Something I ran into when shooting a target at an incline was that my drop was less than what my ballistics calculator said it should be. What I finally narrowed it down to was the shooting position was on ground going slightly downhill and aiming uphill which put my shoulder slightly over and pressing down on the buttstock. This seemed to be causing my shots to go higher than they should have. When someone pointed this out I made sure my shoulder was placed correctly not putting downward pressure on the buttstock and it eliminated nearly all of the difference. Just a possibility you could check.

 

[Darkside-Six]

A 7 degree incline is not something you’ll see a difference in at 500y. It about 0.02mils. Chances are your data is either off somewhere about your MV, or BC.

 

[hlee]

Did you ever resolve the issue? Might be worth confirming the distance with a range finder. 0.4 mil at that distance is the difference between 450 and 500. Then again, it might be worth confirming that your dope and the range are both in meters. If the range were 500 yards that would be enough to explain the difference.

 

[silhouette]

I've only just realised this thread was still alive, sorry for not replying untill now.
Its a square range with a berm at 500m (definitely meters, not yards) and verified with my rangefinder.
I'm using AB and Litz's bc.
Velocity is determined by my CED chronograph.
As far as I can tell I have put in the data correctly and don't seem to have this issue with other rifles.
I haven't resolved it yet (Haven't really tried). Just last Saturday I had the same thing, AB said 2.6mils and I corrected to 2.2.

@phantomskittles has a good point on shooting prone, but its the same regardless of which position I'm in.

Perhaps my velocity is greater than the chrony says and the data on targets nearer than 500m is too close to pick up discrepancies?

 

[Dthomas3523]

Perhaps my velocity is greater than the chrony says and the data on targets nearer than 500m is too close to pick up discrepancies?

Boom

And unless you’ve already verified this, you’re likely hitting higher on the <500 targets than your point of aim and haven’t realized it because of an impact.

Make a water line on the targets. I’m betting you’re hitting high and 500 is where the angle becomes a miss.

 

[silhouette]

I'll also try a friends Magneto speed chronograph simultaneously with my CED when I'm back there in a couple of weeks.
Will keep you posted.