Data not lining up with kestrel

[Tyler25246]

He's not using a BC, he's using a custom drag model specific to his bullet. They are generally more accurate as long as your bullet is operating with the averages they use to parameter the results of the model for that bullet. For some, Litz has custom curves for specific people or rifles for the same bullet. So there's nothing to true as far as BC goes within super sonic.

For subsonic, which is not the OPs problem in this post, there will be another truing option/process called drop scale factor.

Chances are there are other compounding errors that have built up that have trued into the OPs data. It's really not a big deal imo.

So what you're saying is with the custom drag curve he's only going to be changing what the solver uses for MV to match his actual vertical dope, makes sense I've never messed with the custom curves. I should with the applied ballistic fury's just to learn.

From what I'm gathering which In my mind wouldn't matter to me much if true MV vs what the solver uses to give good hits was different.

In your opinion would it be better to run the custom curves and true the MV to get good data or run a BC and true that with actually MV with labradar?

 

[Coyote Shadow Tracker]

So I broke down and bought a kestrel 5700 elite and have been messing around with it a little bit this late summer and fall. I decided to use it on a new load for my .300wsm. 22" bartlein cf wrapped barrel 1:10"
-Norma case
-68.2 grains h-4831sc
-fed 215 primer
-190 berger vld

Off the magnetospeed I'm seeing an ES of around 8-10 and about 2890 fps.

I watched a bunch of videos on the kestrel and followed the instructions and shot my target at 985 yards to true my data. Upon shooting a few times at the target And getting consistent impacts I am confident this should be good data. When I type in my elevation on the kestrel, it is giving me 3105 as my trued velocity. I used the applied ballistics custom curves for the bullet. I know the range is correct. I've ranged the target over and over again and it's the same each time. We trued my buddies 7mm stw the same way and it's giving a believable trued muzzle velocity as well with accurate data. Anyone ever ran into this?

Try going back to the basics and calculate the bullet drop windage with pencil and paper. If you have the bullet weight, BC Velocity no problem. If it is at an angle more than 10-15 degrees and 1,000 yards then need to bring in your algebra skills.

 

[dfanonymous]

In your opinion would it be better to run the custom curves and true the MV to get good data or run a BC and true that with actually MV with labradar?

Fair question. In the matter of opinion, I prefer to just use the custom curve. To me, as long as the data is correct throughout the entirety of its max flight, then I'm good.

That said, I don't have extreme deviations of data, and the worst deviations come from cheap budget setups and using factory ammo. Even they aren't that far off magnetospeed or labradar results.
About the only thing that needs to be trued to a moderate degree is DSF for some manufactures projectiles.

That's my experience anyways.

 

[LaHunter]

So I broke down and bought a kestrel 5700 elite and have been messing around with it a little bit this late summer and fall. I decided to use it on a new load for my .300wsm. 22" bartlein cf wrapped barrel 1:10"
-Norma case
-68.2 grains h-4831sc
-fed 215 primer
-190 berger vld

Off the magnetospeed I'm seeing an ES of around 8-10 and about 2890 fps.

I watched a bunch of videos on the kestrel and followed the instructions and shot my target at 985 yards to true my data. Upon shooting a few times at the target And getting consistent impacts I am confident this should be good data. When I type in my elevation on the kestrel, it is giving me 3105 as my trued velocity. I used the applied ballistics custom curves for the bullet. I know the range is correct. I've ranged the target over and over again and it's the same each time. We trued my buddies 7mm stw the same way and it's giving a believable trued muzzle velocity as well with accurate data. Anyone ever ran into this?

Any chance you are shooting at an up or down angle at your 985 yard trying distance?

 

[JP_Gunner]

I have seen this more often than not and it results in closer range engagements inpacting high. Typically if all data is input correctly and you're still getting a velocity that's way off I will switch off of custom curve and use a g7. I can measure velocity I can't measure BC. So I'll input actually measured velocity then start tweaking BC to line up. BC can change from lot to lot so chances are you have a different lot than was tested.

If switching to G7 and tweaking bc still doesn't line up correctly I'll use drop scale factor to true up.

If you have access to shoot fresh painted targets or paper (either with a waterline) you can get better elevation info than just a hit and will help in inputting good data into kestrel.

One last thing you can try is putting multiple drops in at various ranges to help true out the custom curve, I just got to where I would abandon it if it was that far out.

 

[shootski]

So I broke down and bought a kestrel 5700 elite and have been messing around with it a little bit this late summer and fall. I decided to use it on a new load for my .300wsm. 22" bartlein cf wrapped barrel 1:10"
-Norma case
-68.2 grains h-4831sc
-fed 215 primer
-190 berger vld

Off the magnetospeed I'm seeing an ES of around 8-10 and about 2890 fps.

I watched a bunch of videos on the kestrel and followed the instructions and shot my target at 985 yards to true my data. Upon shooting a few times at the target And getting consistent impacts I am confident this should be good data. When I type in my elevation on the kestrel, it is giving me 3105 as my trued velocity. I used the applied ballistics custom curves for the bullet. I know the range is correct. I've ranged the target over and over again and it's the same each time. We trued my buddies 7mm stw the same way and it's giving a believable trued muzzle velocity as well with accurate data. Anyone ever ran into this?

 

[amork]

I have seen this more often than not and it results in closer range engagements inpacting high. Typically if all data is input correctly and you're still getting a velocity that's way off I will switch off of custom curve and use a g7. I can measure velocity I can't measure BC. So I'll input actually measured velocity then start tweaking BC to line up. BC can change from lot to lot so chances are you have a different lot than was tested.

If switching to G7 and tweaking bc still doesn't line up correctly I'll use drop scale factor to true up.

If you have access to shoot fresh painted targets or paper (either with a waterline) you can get better elevation info than just a hit and will help in inputting good data into kestrel.

One last thing you can try is putting multiple drops in at various ranges to help true out the custom curve, I just got to where I would abandon it if it was that far out.

I think this is the same issue I am having. My 700 yard target is right on, 618 is pretty close. My 300-525 were high, 525 was still on target but 400 was over the top but it's not a very big target. Once hunting season is over I think I'll try this and see if it gives me some better results. I've got my dope now from just shooting at targets every 50 yards and writing dope down but would like it to line up with the kestrel to adjust for environmentals for me. Thankyou!

 

[shootski]

Your location says NorCal so this will be a guess that you did your shooting near that Latitude.
This may help you if you are shooting toward the East and that could make about a 200-300fps difference easily. At the Equator you could get as much as 470+\- or so fps (∆T driven) with an estimated .33 second TOF depending on which direction your barrel is pointing for your testing.

 

[JP_Gunner]

I think this is the same issue I am having. My 700 yard target is right on, 618 is pretty close. My 300-525 were high, 525 was still on target but 400 was over the top but it's not a very big target. Once hunting season is over I think I'll try this and see if it gives me some better results. I've got my dope now from just shooting at targets every 50 yards and writing dope down but would like it to line up with the kestrel to adjust for environmentals for me. Thankyou!

Build a second profile and start playing with it now to sww if it lines up with notes. It's not uncommon for me to have 2 or 3 profiles for a rifle then delete all but one.

 

[VenatusDominus]

Have you verified that your scope is tracking accurately? There was a recent post in this forum where a member tested two scopes and said "So I tested 2 nightforce NX8 4 x 32s one of them was 1.0025 and the other one was .99625 as you can see even in the same manufacturer there's mild error."

Here is an excellent video by Bryan Litz on how to determine and correct for scope tracking errors:

 

[Coyote Shadow Tracker]

Have you verified that your scope is tracking accurately? There was a recent post in this forum where a member tested two scopes and said "So I tested 2 nightforce NX8 4 x 32s one of them was 1.0025 and the other one was .99625 as you can see even in the same manufacturer there's mild error."

Here is an excellent video by Bryan Litz on how to determine and correct for scope tracking errors:

Very good information along with a video. I have Levels on most of our scopes and have a 3' & 4' level at our 100yd target. We level every tatget. We actually line measured the 100yds from the muzzle to the target.
Thanks for this post it will help some shooters.

 

[Euler]

-I'd say 10-12 shots at this distance on steel. Only ones that were a miss were because of wind and also a few finding the right elevation adjustment.
-my zero is rock solid, I've shot quite a few groups at 100 yards and I always go back and shoot a couple at 100 before going out in distance just to verify. It's always came back and this scope has always tracked. It's a nightforce atacr 5-25.
-units are correct, I verified that a couple times over.
-mv was done at a different time with warmer temps. I didn't think 4831-sc was to temp sensitive so didn't take that into consideration, not enough to cause 215fps of difference anyway.
-I guess there could be some of me involved in it but with the same exact setup except a stainless barreled 6.5prc on the same action/same scope/same stock, using the shooter app and the magnetospeed mv I didn't have any issues and I shot that at every distance from 100-1317 yards repetitively.

I'll look over all the settings again on the kestrel to verify your guys points because I have got to be missing something. There's no way a 300wsm with a 22" barrel and a 190 grain bullet could fly that fast.

Right on!

Just for reference, at my location, that bullet in the range of MV that you've listed results in about 0.1 mil of elevation difference per about 17 fps of MV at 1,000 yards.

-A difference of about 5 yards in range equates to about 0.1 mil (correlating to about 17 fps difference).

-Depending on how many shots you chrono'd to get that ES & avg MV, your SD may or may not be higher than you think and the confidence interval may also be higher than you think (meaning both your avg MV & SD/ES is not what you think).

-It's extremely rare to have a dead nuts zero (no height or elevation offset) over a statistically significant number of shots. I'm not saying you have to go shoot 35 - 50 rounds, but I am saying you might not realize that you actually have a zero offset. A 0.36" zero height offset correlates to about 17 fps at 1,000 yards

-The difference in scope height above bore of about 0.4" correlates to about 0.1 mil at 1,000 yards (17 fps difference).

-I've owned ATACRs that don't track 100%, but are close. Most people won't be able to notice a scope that's a few percent from 100% unless you're performing the right kind of checks. At 1,000 yards, a scope that tracks 97% (for example) could correlate to about 0.2 mils of difference (about 34 fps)

-If you aren't actually tracking the exact POI/POA difference at distance, it's pretty easy to be 0.1 - 0.2 mils off waterline without knowing it (correlating to 17 - 34 fps)

- how are you determining that your scope is plumb with gravity? If you're canted, you will start seeing some elevation discrepancies that could be conflated with MV issues. Not all reticles are installed square to the turrets, and some companies will say 1 degree of cant is within spec. So depending on if you dial or hold over, that error could raise its head.

-did you zero in the same/similar wind condition as you dope'd out your gun? Is your solver doubling down on AJ? That could add a little bit of elevation discrepancy that is seen as MV difference.



I'm typically of the mindset that I true my calculator based on real world data. BUT, the amount that I true should be reasonable. Otherwise your solver will only be good for a single circumstance, and you'll end up with errors if the environmentals change. The only reason I give the above examples is to show how it's pretty to be off by 50 - 100 fps in MV unless you're diligent in accounting for everything. A difference of 215 fps would be a red flag that I've got issues in my inputs somewhere.

 

[okie man]

This is why I prefer a scope with moa/mil marked type reticules. They are easy to verify and never go out of whack after that. 707 yards, hold between 14 and 16 moa marks and send it. Just gotta play the wind game

 

[TulsaGrizz]

Use the Kestrel to get environmental information......then use Strelok Pro. I never got AB to work with my 6mm GT, but Strelok is dead nuts? Go figure, could have saved a lot of money on a cheaper wind meter.