Kestrel dope questions....

[jaybic]

Hello all,
I am hoping someone can point me in the right direction on something. I Shot a two day NRL match in South Dakota and it and on one stage I was shooting 1251yds essentially straight west with a 10 MPH wind from the south(9 oclock). Shooting a 6x47 and 105 hybrids at 3000 fps. Kestrel called for 10.5 mils. Hit both shots. 2 stages later I am shooting at 1240 almost 180 degrees the opposite direction(east). Same 10 mph wind but is now 3 oclock(still from the South) relative to direction of shot. Kestrel now calls for 10.0 mils. did not believe kestrel and instead went with proven dope(obtained on an east facing range back home....missed both shots.

Came back to same stage on Day 2 and shot 1240 again. wind is also 10 mph but is now from the North(which makes it 9 oclock) and now Kestrel is calling for 10.7 mils of elevation. 10.0 to 1240 on day 1 with a south wind and 10.7 on day 2 with a north wind. Can it really be that much??? I understand(or maybe I dont) crosswind jump and the idea of Magnus affect but are these numbers real? should I have believed the Kestrel? and if so how do I know when to and when not to? I use the clock method and gathered target direction and wind direction by capturing on the Kestrel prior to shooting the stage. I also understand( and again, perhaps not) the idea of Coriolis affect and spin drift or I am at least aware that these things exist but the same distance being .7 mils different one day to the next AFTER I had already hit(verified dope albeit different direction and wind conditions?) seems a bit unreal. Or am I refusing to believe the Kestrel and talking myself out of points?

Thanks and sorry to carry on but I wanted to paint the best picture I could to get the best answer I could.

Jamie

Thanks for the help

 

[LawnMM]

Sounds like AJ to me, whether it's correct is another story.

They talked about this on the podcast, if you want to see how much it's adding for AJ set your Kestrel for the distance and wind, then reverse the wind 180 degrees.

Something like that anyway, you can zero the AJ effect by setting WS1 to zero and just using WS2 for wind calls.

I could see it change by a tenth, maybe two, 5-7 seems like a lot. It may be adding in Coriolis and SD and all that jazz too.

I'd go shoot it and try to mimic the directions of fire and distance and see what predicted vs actual looks like for hits.

Then start turning things on/off till they match up.

 

[Dthomas3523]

At that distance, a DA change of 2000ft can have about a .5 difference.

Depending on how much temperature changed and such, that could be why.

Spin drift, coriolis, and aerodynamic jump, if using these, could also be adding to it.

If you trued the kestrel properly, I’d pretty much trust it. By trued property, I mean having the correct settings turned on/off and dope lining up for at least a 2k change in DA.

 

[jaybic]

Which podcast if I may ask? I believe my kestrel is trued properly but I could be mistaken
Trued with FPS At 600 and adjusted BC at 1200. DA unknown at the time. Didn't think to note and record it now that you say that. As for 2000 DA change...possible on day 2 as it was cloudy and rained all night but on day 1 the stages were identical conditions a half hour apart. Maybe you fellas are right...maybe a 10th of this, that and the other thing all adds up....just seems hard to believe


Wow...

 

[LawnMM]

Everyday Sniper Podcast

 

[Dthomas3523]

We’re you able to see how you missed?

1200+ yds, lots of little things can add up quick.

Knowing as exact as possible where you impacted will help. If you don’t know where the rounds went, there’s zero chance of diagnosing the issue.

 

[_Windrider_]

Also, only use wind 2. This removes a lot of the noise.

 

[seansmd]

From my recollection:
AJ: as stated above set W1 to ZERO to negate its affects
Spin Drift: disabled in the profile
Coriolis: set DOF to zero degrees-- EDIT-- @Dthomas3523 correction set latitude to ZERO
magnus: I assume you would need to do the above AJ off, DOF zero, spin drift off and change the wind from 270 to 90 and see the difference

If you are playing with the settings you can go into the ballistics menu and it will show you what is contributing I believe

 

[Dthomas3523]

From my recollection:
AJ: as stated above set W1 to ZERO to negate its affects
Spin Drift: disabled in the profile
Coriolis: set DOF to zero degrees
magnus: I assume you would need to do the above AJ off, DOF zero, spin drift off and change the wind from 270 to 90 and see the difference

If you are playing with the settings you can go into the ballistics menu and it will show you what is contributing I believe

Coriolis isn’t DoF. It’s latitude set to zero.

DoF can be set normally with degrees or clock preference.

 

[seansmd]

Coriolis isn’t DoF. It’s latitude set to zero.

DoF can be set normally with degrees or clock preference.

Right, my bad! Edited the original

 

[Sogan]

From my recollection:
AJ: as stated above set W1 to ZERO to negate its affects
Spin Drift: disabled in the profile
Coriolis: set DOF to zero degrees-- EDIT-- @Dthomas3523 correction set latitude to ZERO
magnus: I assume you would need to do the above AJ off, DOF zero, spin drift off and change the wind from 270 to 90 and see the difference

If you are playing with the settings you can go into the ballistics menu and it will show you what is contributing I believe

Newish kestrel user here, is this the ideal settings for the kestrel to get more accurate results or just something to mess with to see the effects of each?

 

[seansmd]

Newish kestrel user here, is this the ideal settings for the kestrel to get more accurate results or just something to mess with to see the effects of each?

These are the settings recommended by those in the know to disable the solver from adding effects that are not needed or are over emphasized in the software.

 

[Mordamer]

When I got a Kestrel I doubted it when sitting at home and playing with the numbers. I noticed the same thing, that the wind direction and direction of fire made a bigger dope difference than what I expected. I decided to do my own test. I found a spot on the ranch where I could shoot at 1,000 yards east and west. There was a pretty decent crosswind. Kestrel ended up being right in both directions even though it provided me with pretty wildly different results for both directions. Since then I have trusted it.

On a side note, I have learned to reduce wind 1 on the kestrel if I am shooting from a location where the crosswind at the muzzle is less than the average wind for the rest of the bullets flight. This reduces the calculated Aerodynamic Jump.