Kestrel truing challenge

seansmd

In a minute man
Belligerents
Minuteman
Aug 8, 2018
1,182
812
119
San Jose, CA
Hi Folks,

I could use your help, this is the first time I have been challenged at getting my data to line up with verified DOPE. The kestrel 5700 elite with custom curve on Hornady ELDM 140g on 2 rifles has always been spot on out to 1K for me, and always lined up almost perfectly with Hornady 4dof, Streelock Pro, and Ballistic ARC.

This is where I have a challenge, my new rifle, started speeding up as expected after a couple hundred rounds, I observed this in a match and couple of recreational shoots. I decided to do a clean, fouling(MV measurements with MS since I have it , verify zero. Then this weekend verify all dope from 100-900 yards.

I have used the process:
1) solid zero on a measured LRF verified distance 103Y
2) validated DOPE on LRF verified distances of 3+ shot groups on fresh painted steel with water mark and a spotter.
3) Adjusting MV in the tools @`600 yards, then adjusting BC @~800yards if needed.

At the range I used the Kestrel for the try dope(column B), wrote it down, adjusted and wrote down the TRUE DOPE (column C). I did this for all LRF verified ranges, shooting from 200 yards out to 900 yards on steel that was freshly painted and had a water mark. I worked with a spotter and we spotted and verified each others shots on each target, most ranges we each had our own targets, but on the larger gongs we were able to differentiate very easily. I added a drone picture of the 900 yard target.

Then at home using various apps used the 598 yard target to true up the MV, and this worked well for Ballistic ARC, Strelok Pro, and Hornady 4DOF (column D). I captured all of the environmental data from the session as captured by the kestrel and written down, and locked the Kestrel.
1/19/2020 Avenal Gun Club, 9AM, MPA 6.5CM, Defiant Deviant, Bartlein M24
Scope over bore 2.3", Zero verified range 103y, no offsets
41 degrees, 29.27 inHg, 90% RH, -350 DA, 37 LAT
All targets Zero angle, zero DOF, no wind entered, no wind on range
Hornady ELDM 140g

The new MV for all of these to line up was 2790 and no BC correction. I expected as I have before to go into the Kestrel adjust the MV to 2790 and it would line up as well. This is not what happened and the data was significantly off from 500 yards and out, and I could not get the custom curve to line up at all (column E&F). I created another profile with the G7 BC and captured the results (column I) it was off as well but with MV and BC was able to get it close. As I was finishing this Kestrel pushed the 1.36 update and it moved the numbers as well. captured below.

The result is I had to move AWAY from the AB custom curve to get any data to line up. I tried the DSF but it had no impact as I believe 600-900 yards is too close for this to have an effect. This is the hardest I have had to work to get my Kestrel to line up with verified dope. Are others seeing any anomalies with Hornady ELDM in the AB SW not lining up?

An interesting side note, I also re-verified the Prime 130g USA (new ammo), and the profile I had was still spot on at all these ranges. same environmental data. Verified the Prime after the Hornady at each range.

sorry for the book, but tried to provide as much data and background on the process I used. End of the day I have my dope, and will print out new wrist coach cards and DA charts, but a little bummed on the Kestrel.

1579564478814.png

1579564512793.png
 

LawnMM

Harbinger of Sarcasm
Belligerents
Jul 5, 2009
3,187
2,659
219
Colorado
What was the MS measured MV?

The custom curve at 2810 after update looks dead nuts, did you change your zero range to 103yds in the gun profile?
 
  • Like
Reactions: seansmd

seansmd

In a minute man
Belligerents
Minuteman
Aug 8, 2018
1,182
812
119
San Jose, CA
What was the MS measured MV?

The custom curve at 2810 after update looks dead nuts, did you change your zero range to 103yds in the gun profile?
MV measured by the MS increased by about 25fps, from 2760 to 2785

I modified an existing profile to limit the possibility of creating it differently or enter something wrong. So zero distance is consistent.

The 2810 CC after the update is pretty close but it is 20fps faster than the other tools, and +0.1mil at 900 which is fine but the first time this was needed for me. Both 1.35 and 1.36 were updated in the last week+? that is bothersome, 1.35 is pretty far off 0.15mil @900, 0.1mil at 800
 

LawnMM

Harbinger of Sarcasm
Belligerents
Jul 5, 2009
3,187
2,659
219
Colorado
You may get more speed yet. My first CM barrel was 200fps slow. Box of ammo said 2925 or something and I was getting 2725ish.

How many rounds on the new barrel?
 
  • Like
Reactions: seansmd

seansmd

In a minute man
Belligerents
Minuteman
Aug 8, 2018
1,182
812
119
San Jose, CA
You may get more speed yet. My first CM barrel was 200fps slow. Box of ammo said 2925 or something and I was getting 2725ish.

How many rounds on the new barrel?
A little over 800, I already saw the initial increase, it started at 2685, settled at 2760, now 2785.
 

LawnMM

Harbinger of Sarcasm
Belligerents
Jul 5, 2009
3,187
2,659
219
Colorado
2785 is pretty close to 2810, did you set direction of fire in the Kestrel? Double check wind direction if you use the capture feature as in my experience it often captures the correct speed but the wrong angle
 

seansmd

In a minute man
Belligerents
Minuteman
Aug 8, 2018
1,182
812
119
San Jose, CA
Yeah had them all zero out in the app and sent them to the device, even did a factory reset too.

I was all done when the 1.36 released this afternoon so I added that data. My worry of sticking with the CC is it will diverge further at 1k and beyond.

I will use ballistic Arc for my paper dope, and the G7 on the kestrel with the higher mv and changed bc.
 

seansmd

In a minute man
Belligerents
Minuteman
Aug 8, 2018
1,182
812
119
San Jose, CA
I just realized the factory reset turned Spin Drift back on and the delta over TRUE DOPE is worse. Any adjustment up more on MV is going to destroy the close yardages.

Below RED text is modified after turning Spin drift back off. Looks like for the Kestrel, my solution is G7 MV 2830, BC modified to 0.300 (from 0.291).

1579572235875.png
 

Matches Malone

Jihad Joe
Belligerents
Mar 6, 2017
367
178
49
Your moms bed
I just realized the factory reset turned Spin Drift back on and the delta over TRUE DOPE is worse. Any adjustment up more on MV is going to destroy the close yardages.

Below RED text is modified after turning Spin drift back off. Looks like for the Kestrel, my solution is G7 MV 2830, BC modified to 0.300 (from 0.291).

View attachment 7230230
The bc you trued to looks better for what hornady recommends. This might have saved you time by looking up BC by mach 2.5. Hornady recommends starting with .320

 
  • Like
Reactions: seansmd

seansmd

In a minute man
Belligerents
Minuteman
Aug 8, 2018
1,182
812
119
San Jose, CA
The bc you trued to looks better for what hornady recommends. This might have saved you time by looking up BC by mach 2.5. Hornady recommends starting with .320

Hornady 4DOF was spot on, I was hoping that AB is staying up to date with the BC. I didn't choose it I selected it form the latest AB library updated today in the 1.36 release. Up until today I have been using the AB custom curve no BC.
 
  • Like
Reactions: JfarmshooterW

Matches Malone

Jihad Joe
Belligerents
Mar 6, 2017
367
178
49
Your moms bed
Hornady 4DOF was spot on, I was hoping that AB is staying up to date with the BC. I didn't choose it I selected it form the latest AB library updated today in the 1.36 release. Up until today I have been using the AB custom curve no BC.
Ah. I don’t use the custom drags on my kestrel. Just because I don’t know how they conduct the testing. Interesting though. Maybe I’ll play around with the custom drag library some.
 
  • Like
Reactions: seansmd

seansmd

In a minute man
Belligerents
Minuteman
Aug 8, 2018
1,182
812
119
San Jose, CA
Seansmd, do you have a DSF stored on the profile, don't know if I caught that in your first post.
I didn't and when I saw it diverge I tried to use the dsf to bend it at 600,700,800,900 but it didn't change it at all, I think it's too close. I may be doing it wrong. I went into that menu for the distance it shows the suggested elevation, I adjusted it down to the true dope, hit exit, chose enter to save. When it didn't work I deleted it. Verified there were no entries.
 

Jabot

Private
Belligerents
Minuteman
Sep 2, 2014
341
103
49
For what its worth I couldn't get my kestrel to match my dope from yesterday either
 
  • Like
Reactions: seansmd

Diver160651

Who cares
Belligerents
Feb 7, 2013
4,111
3,215
219
BELMONTCA
I didn't and when I saw it diverge I tried to use the dsf to bend it at 600,700,800,900 but it didn't change it at all, I think it's too close. I may be doing it wrong. I went into that menu for the distance it shows the suggested elevation, I adjusted it down to the true dope, hit exit, chose enter to save. When it didn't work I deleted it. Verified there were no entries.
  • First do NOT expect the velocity or BC needed to make the click accurate impacts between competing programs as an absolute. More often than not, the data between the AB solvers is not 100% =; It's close enough, but you'll see it from your desk. Remember you need to give the program what it needs to work and it may be slightly more or less velocity than another program needs.
  • The DSF is not what you want to use at this close range. It will really screw you total curve.
  • CC's a fast way to get good enough dope for most people, not as good as perfectly tuned DC in many cases - especially if you're expecting paper tuning accuracy.
  • Hopefully you have written all the actual DOPE including the environment and true yardage.. Ie 595, 890 not what the range really lists.
    • With than you can turn off "live update" and reenter the conditions into your Kestrel. From their you can use a custom drag curve and reverse engineer your profile.. You should be able to get a result equal to your dope. Then then live update back on and run both solvers you mentioned they should line up fairly well untill you get in transonic.
      • At the true distance for your 600, aline the velocity, BEFORE touching the drag
      • Then at 900's true yardage adjust the drag. Note that you might need to balance the numbers slightly, mostly due to not shooting benchrest quality groups on paper and using a caliper to truly ensure your impacts are as you think.
Edited to add _ I run it in AB
 
Last edited:
  • Like
Reactions: Spooky68

seansmd

In a minute man
Belligerents
Minuteman
Aug 8, 2018
1,182
812
119
San Jose, CA
Ok, very interesting just spoke with @Diver160651 and confirms what @Matches Malone indicated above, Hornady and the older version of the kestrel use a 0.321 G7 BC. My 1.36 version library on the app is 0.291, that's a huge difference and why it was calling it high at distance. I will no longer let the kestrel update once I have it lined up. The gun sped up a little, and AB and/or kestrel messed up the BC for the hornady 140geldm.
 

Diver160651

Who cares
Belligerents
Feb 7, 2013
4,111
3,215
219
BELMONTCA
For fun, what was your actual direction of fire?
about .01mil and his longest shot arguably the same but the calculator might spit out an extra .01 -- his shot direct is 90° from 100- 500 and 600 thru 900 350°

FYI copied from the Hornady Website:

6.5mm 140 gr. ELD Match
MACH 2.25 (roughly his MV)
0.646 G1​
0.326 G7​
MACH 2 (reached by 420y in his DA and MV)
0.637 G1​
0.320 G7​
Gotta say Horndy's Doplar seems spot on to his numbers
 
Last edited:
  • Like
Reactions: seansmd

lte82

Shooter
Belligerents
Mar 12, 2013
1,762
891
219
about .01mil and his longest shot arguably the same but the calculator might spit out an extra .01 -- his shot direct is 90° from 100- 500 and 600 thru 900 350°

FYI copied from the Hornady Website:

6.5mm 140 gr. ELD Match
MACH 2.25 (roughly his MV)
0.646 G1​
0.326 G7​
MACH 2 (reached by 420y in his DA and MV)
0.637 G1​
0.320 G7​
Gotta say Horndy's Doplar seems spot on to his numbers
Gotcha. 350 is close enough to 0. I know when truing beyond 800 direction of fire starts to become important.

Yes, .320 is probably very close. I know the 147's vary about .005 in my two barrels. .334 vs .339. Not a lot but enough to where you might decide to round your elevation up instead of down and be a bit off at distance. But it's very close to what Hornady publishes.

My guess is that the .291 was a mistake on AB or Kestrels part. Sounds like the old 140 amax BC...
 
  • Like
Reactions: seansmd

seansmd

In a minute man
Belligerents
Minuteman
Aug 8, 2018
1,182
812
119
San Jose, CA

Kestrel Ballistics

Commercial Supporter
Commercial Supporter
Belligerents
Feb 2, 2018
485
359
69
Boothwyn PA
kestrelinstruments.com
The hornady recommended BC for the 140g ELDM is 0.326 to 0.320, the latest 1.36 library is loading 0.291 which is a pretty large difference.

I don't know when it changed, @Diver160651 version (he hasn't updated his kestrel) pulled 0.321 I believe. It was seeing in both 1.36 and 1.35 not sure before that.

https://www.hornady.com/support/ballistic-coefficient

Thank you for the help on this.
If you are referring to the AB Kestrel, AB does modify BC based on testing, so it is not unusual to see different BC numbers in the library.
 

seansmd

In a minute man
Belligerents
Minuteman
Aug 8, 2018
1,182
812
119
San Jose, CA
If you are referring to the AB Kestrel, AB does modify BC based on testing, so it is not unusual to see different BC numbers in the library.
Yes AB and the difference in the BC is very significant and changed recently. It's off by over 10% which was suggesting 0.3mils high at 900 yards.
 

Diver160651

Who cares
Belligerents
Feb 7, 2013
4,111
3,215
219
BELMONTCA
No reflection on the Kestrel, this is another AB update issue. I’ve learned to stay away from updates from AB if I am already working. Truth be told, I use my Kestrel to get absolute station when traveling, but default to other methods to create my drop charts.

From ABs new library-
4057C5B9-EEF4-4F16-B834-6492B07F6B17.png
From Hornady web
BF28507C-17CC-4DF8-866D-5A19C085ECCE.png

From a program that seems to be close:
9F6907E3-7403-4183-8D93-110A27168D92.png
 
  • Like
Reactions: seansmd

seansmd

In a minute man
Belligerents
Minuteman
Aug 8, 2018
1,182
812
119
San Jose, CA
And the bullet doesn't lie, the Hornady BC and the MV closer to the measured Chrono are looking up to real world verified dope.

Either AB has a typo that has propagated across platforms, or they are basing this on MV that common platforms and factory ammo are not producing.
 

seansmd

In a minute man
Belligerents
Minuteman
Aug 8, 2018
1,182
812
119
San Jose, CA
Hi @DocUSMCRetired can you comment on the Hornady ELDM 6.5CM in the latest library?

It seems the library has it with a G7 of 0.291 and the custom curve seems to line up with this number. Hornady's website is recommending 0.326 - 0.320 depending on MACH. This is a pretty large difference and looks like the October library release changed for this bullet.

My trued dope(up in the thread) aligns with a 0.321 BC. The custom curve, or the one default in the library (0.291) could not get lined up.
 

Indybio72

Private
Minuteman
May 10, 2018
27
38
18
Hi @DocUSMCRetired can you comment on the Hornady ELDM 6.5CM in the latest library?

It seems the library has it with a G7 of 0.291 and the custom curve seems to line up with this number. Hornady's website is recommending 0.326 - 0.320 depending on MACH. This is a pretty large difference and looks like the October library release changed for this bullet.

My trued dope(up in the thread) aligns with a 0.321 BC. The custom curve, or the one default in the library (0.291) could not get lined up.

Anyone have an update on this?
 
  • Like
Reactions: seansmd

BLKWLFK9

Just F'n Send It..
Online Training Access
Belligerents
Feb 13, 2017
1,890
2,409
219
This is why i gave up on AB a long time ago. I couldnt get it to line up well at all. To get it close, i had to lie to it very much. Ive been using strelok pro and 4dof ever since with 0 issue. No lying on MV and barely have to move BC, G7 or G1. I bought a 4dof kestrel this week, should get here friday. Im excited about having a kestrel that i believe in b/c i hate using my current kestrel for enviromentals and inputting it into my phone. I like and trust 4dof enough to roll with it 100% of the time.
 
Last edited:

Indybio72

Private
Minuteman
May 10, 2018
27
38
18
This is why i gave up on AB a long time ago. I couldnt get it to line up well at all. To get it close, i had to lie to it very much. Ive been using strelok pro and 4dof ever sense with 0 issue. No lying on MV and barely have to move BC, G7 or G1. I bought a 4dof kestrel this week, should get here friday. Im excited about having a kestrel that i believe in b/c i hate using my current kestrel for enviromentals and inputting it into my phone. I like and trust 4dof enough to roll with it 100% of the time.
Hope the 4dof kestrel works well for you. I havent tried that program yet. Already have the 5700 elite so I'm going to stick with it for now. Just hope to get an answer on this bc stuff, since I like to use the custom curves but you cant adjust BC, so if it's off your pretty much SOL
 
  • Like
Reactions: BLKWLFK9

seansmd

In a minute man
Belligerents
Minuteman
Aug 8, 2018
1,182
812
119
San Jose, CA
This is why i gave up on AB a long time ago. I couldnt get it to line up well at all. To get it close, i had to lie to it very much. Ive been using strelok pro and 4dof ever sense with 0 issue. No lying on MV and barely have to move BC, G7 or G1. I bought a 4dof kestrel this week, should get here friday. Im excited about having a kestrel that i believe in b/c i hate using my current kestrel for enviromentals and inputting it into my phone. I like and trust 4dof enough to roll with it 100% of the time.
Giving @DocUSMCRetired and the AB team a chance to find an error in the database. The AB BC is very different and not aligned with the mfg, any other calculator, or the real world dope.

I love the idea of 4dof and the app is money in the eldm but does not yet support prime ammo in 6.5cm or the bullet in 4dof so you need to build and lie to it just like AB.

Truing MV is fine and my AB based kestrel is looked in out past 1k, but only because folks here helped identify that the BC was wrong. Once that assist was made the mv was very close to my magnetospeed.
 

BLKWLFK9

Just F'n Send It..
Online Training Access
Belligerents
Feb 13, 2017
1,890
2,409
219
I trued my 4dof kestrel in about 4 min. Correct mv and barely touched the AFF and it lines up 100%. I do wish hornady would add the 95tmk and 95smk to the library for 4dof.
 
  • Like
Reactions: seansmd

Indybio72

Private
Minuteman
May 10, 2018
27
38
18
I trued my 4dof kestrel in about 4 min. Correct mv and barely touched the AFF and it lines up 100%. I do wish hornady would add the 95tmk and 95smk to the library for 4dof.
I'm referring to the incorrect BC for the 140eldm, both the g7 and the CC are using a BC of .291 which is wrong
 

Indybio72

Private
Minuteman
May 10, 2018
27
38
18
Just installed the newest 1.39 kestrel update. They fixed the CC model for the 140eldm. It now lines up with a roughly .320 g7.

However if you select to use the g7 model rather than CC, they still are using a .290 BC.

So at least they halfway fixed it
 
  • Haha
Reactions: seansmd

seansmd

In a minute man
Belligerents
Minuteman
Aug 8, 2018
1,182
812
119
San Jose, CA
Just installed the newest 1.39 kestrel update. They fixed the CC model for the 140eldm. It now lines up with a roughly .320 g7.

However if you select to use the g7 model rather than CC, they still are using a .290 BC.

So at least they halfway fixed it
That is crazy!
 
  • Like
Reactions: Stephentri