Episode 92

[Nik H]

Frank,

In episode 92 you talked about using the MV truing function within the Kestrel. You mentioned that the corrected MV was so far off that you didn't use it but relied on your own method.

I have experienced the same thing. I had measured my MV accurately. Caliber is 6.5mm Creedmoor. 10 shots of Hornady 140 grain ELD-M with an average of 2704 fps, ES of 32 and an SD of around 8. Predicted drop by the Kestrel at 500 was 2.8 mils. Actual DOPE was 2.5 mils. Used the truing function and it changed MV to 2812 fps. I am like WTF?

Could you please describe the method you described where you tweak both MV and BC.

 

[_Windrider_]

We beat this horse into glue here

https://www.snipershide.com/shooting/threads/truing-mv-vs-bc.6891826/

 

[Nik H]

We beat this horse into glue here

https://www.snipershide.com/shooting/threads/truing-mv-vs-bc.6891826/

 

[Nik H]

We beat this horse into glue here

https://www.snipershide.com/shooting/threads/truing-mv-vs-bc.6891826/

I read through that thread. The reality is that much of what you talked about along with @Skookum made a lot of sense. However, I don't have access to an 800 yard range anywhere around me. The longest is 600. Therefore, it would not be possible to follow your process until I get to a longer range. I am taking a class in 3 weeks in upstate NY where we will be shooting from 600 -1400 yards so I will definitely be able to follow your collective advices at that time.

It just boggles my mind that AB can't properly predict drop at 500 with a known good velocity. And this time I zeroed so know that was solid and was firing at a bullseye target. I fired two groups of five shots. My group sizes were 0.44 and 0.68 MOA. Target was retrieved and measured to determine actual drop.

 

[Lowlight]

I like glue, smells great in the morning, a little bit in the afternoon and sniff before bed LOL

You can still tweak the BC a bit and then you will also move the MV a bit. It's a compromise when you don't have access to the range.

Unfortunately changing the MV is how that particular software operates, if you want to use your real-world data and be super close to right, invest in TRASOL

 

[Nik H]

I like glue, smells great in the morning, a little bit in the afternoon and sniff before bed LOL

You can still tweak the BC a bit and then you will also move the MV a bit. It's a compromise when you don't have access to the range.

Unfortunately changing the MV is how that particular software operates, if you want to use your real-world data and be super close to right, invest in TRASOL

I did Frank. At 500 yards both apps are pretty close in their predictions and off from the real data. Both predict a drop of approximately 2.9 mils using an MV of 2721, DA of 1051 ft, and G7 of 0.305. Real drop was 2.5

 

[Lowlight]

Is the range right?

We do see public ranges with incorrect ranges, the 500 could be 515, just saying

 

[_Windrider_]

I did Frank. At 500 yards both apps are pretty close in their predictions and off from the real data. Both predict a drop of approximately 2.9 mils using an MV of 2721, DA of 1051 ft, and G7 of 0.305. Real drop was 2.5

Try G1 and tweak it until it matches. Shouldn’t have to move it very far. In addition, don’t use DA, use the real environmental inputs (station pressure, temp and RH).

 

[Nik H]

Is the range right?

We do see public ranges with incorrect ranges, the 500 could be 515, just saying

It actually is 510 yards as measured by my LRF, I just rounded it in my conversation.

 

[Nik H]

Try G1 and tweak it until it matches. Shouldn’t have to move it very far. In addition, don’t use DA, use the real environmental inputs (station pressure, temp and RH).

I recorded those so I will try it

 

[Deleted member 113831]

I have no idea what your conditions might have been, but I am going to put this out as a possibility...

Anytime I hear or read of someone's dope not lining up at a distance as close as 500 yds, I wonder about the lighting comditions. Light can very easily make a 1MOA (0.3 mil) change at any distance. Bbut it is at the closer distances, where other environmentals are diminshed in effect, that light can make the most drastic difference as a percentage of total drop and completely skew the numbers.

When you do these tests, you have to confirm zero, and shoot the long target AT THE SAME TIME. You can't rely on a previous zero!!

I am not saying this is the case, just something to think about.

 

[Nik H]

I have no idea what your conditions might have been, but I am going to put this out as a possibility...

Anytime I hear or read of someone's dope not lining up at a distance as close as 500 yds, I wonder about the lighting comditions. Light can very easily make a 1MOA (0.3 mil) change at any distance. Bbut it is at the closer distances, where other environmentals are diminshed in effect, that light can make the most drastic difference as a percentage of total drop and completely skew the numbers.

When you do these tests, you have to confirm zero, and shoot the long target AT THE SAME TIME. You can't rely on a previous zero!!

I am not saying this is the case, just something to think about.

I did this based on your suggestion last time @Skookum. I confirmed zero at 100 yards and then shot two 5 shot groups at two different but adjacent targets.

I must be doing something so fundamentally wrong that it isn't obvious

 

[Deleted member 113831]

I did this based on your suggestion last time @Skookum. I confirmed zero at 100 yards and then shot two 5 shot groups at two different but adjacent targets.

I must be doing something so fundamentally wrong that it isn't obvious

That's good. That means it is one more thing you can eliminate.

 

[Nik H]

That's good. That means it is one more thing you can eliminate.

What about parallax? What if it is off?

 

[Deleted member 113831]

@Nik H We've talked about generalities, so let's hear the specifics:
You told us the bullet and speed, what BC are you using?
Are you using DA or Station Pressure?
What is the actual altitude and temp?
What is the scope height above bore?
Is there an incline or decline angle?

 

[Deleted member 113831]

What about parallax? What if it is off?

It could be off, but it is pretty unusual to shoot groups as tight as you are saying with a jacked up parallax. Besides, you checked it didn't you?

 

[Nik H]

@Nik H We've talked about generalities, so let's here the specifics:
You told us the bullet and speed, what BC are you using?
Are you using DA or Station Pressure?
What is the actual altitude?
What is the scope height above bore?

DA - 1041 feet.
Altitude - 122 feet
Scope Height is 2.08"

 

[Nik H]

It could be off, but it is pretty unusual to shoot groups as tight as you are saying with a jacked up parallax. Besides, you checked it didn't you?

I did and you are right but I am reaching

 

[Deleted member 113831]

I did and you are right but I am reaching

I ran your numbers and got the same prediction in Strelok... 2.9 mils.
What is the terrain like between the firing point and 510 yards?
What is your confidence level in the velocity? 2700 seems a bit low.

 

[Nik H]

I ran your numbers and got the same prediction in Strelok... 2.9 mils.
What is the terrain like between the firing point and 510 yards?

It is flat from the firing line to the first berm at 200. After the berm, it is pretty flat to 500 yards.

Is 0.3 mils error between predicted and actual too much of an error in your experience?

 

[Deleted member 113831]

It is flat from the firing line to the first berm at 200. After the berm, it is pretty flat to 500 yards.

Is 0.3 mils error between predicted and actual too much of an error in your experience?

PM Sent

 

[JMGlasgow]

Would the scope turrets not tracking be causing your issue? Have you checked them?

 

[Nik H]

Would the scope turrets not tracking be causing your issue? Have you checked them?

Did two tall target tests...no issues.

I think the culprit is lighting and mirage. This Sunday the weather is forecast to be cool and cloudy so it will be very telling