Ballistic Calculators Discrepancies?

[AM_Hunter]

For some weird reason, the ballistic calculators im using all seem to have a kind of decent discrepancy on their calculations.

For pre-tense, im shooting a federal power-shok copper .308 150gr out of a 24" 1:10R twist remington 700.

I am using 3 Ballistic Calculators, MD Ballistics (Mobile), Hornady (Mobile), and Vortex (Web based).

At 500' elevation they all have about the same adjustments out to 700 Yards.

However, at 8000' elevation, at 700 yards im getting 5.1 Mil with MD, 6 Mil with Hornady, and 5.3 mil with Vortex.

I have triple checked all the rifle/ammo inputs, the BC, velocity, zero range, sight height, etc and they all match. I also made sure the elevation, pressure, temperature, and RH are the same for all three. What could be causing this large discrepancy? 0.9 Mil between MD and Hornady is quite a bit at 700, that's almost 2 feet.

Additionally, when using the MD ballistic app, I have the option to use density altitude, which means I only put in the elevation and i think it uses that to assume temperature, pressure, and RH, that changes the 700 yard adjustment from 5.1 Mil to 6.3! I also have the option to select "pressure is absolute", which removes the option to adjust elevation, and which brings the 700 yard mil adjustment to 6.1 mil.

Any ideas on which one is correct? Is there some variable that plays a bigger factor that I may be missing?

I'm heading to the range which is at 500' elevation to shoot out to 700 yards tomorrow to check my mils but since they are so close at 500' i dont think itll answer which is more accurate at 8000'. I dont plan to take a shot out to 700 but I just want to be prepared and also better understand and trust my calculators and also learn for long range recreational shooting.

Any input would be appreciated, thanks!

 

[AM_Hunter]

Test to see if the one I was using was accurate

 

[def90]

Do any of them account for the powder type? Basically what you are finding is that there is still a bit a black magic going on when it comes to balistic calculators which is why serious long range shooters stick with a specific load/powder/projectile and so on and then shoot a lot at various ranges to develop their own dope chart.

Errors are magnified the further you go out.

 

[Marble]

Ballistic calculators are for getting a baseline and not for final use. Confirmation needs to happen.

As for the discrepancy, I would ask the maker of each program and see what they say. I don't think anyone here will know.

Sent from my SM-S918U using Tapatalk

 

[WeiserBucks]

Test to see if the one I was using was accurate

Which one makes your impacts land where they're supposed to?

 

[Wrench]

My data changes when paired to the kestrel. The kestrel data changes when in the truck to field.

Atmospheric sensors are awesome....but they also introduce change.

 

[Megalodon]

DA =/= elevation

 

[sndmn11]

My dad downloaded the Hornady one because we couldnt find strelok.

It's wonky as heck. If you move the wind from RL to LR it changes the elevation adjustment drastically.

 

[Reburn]

My dad downloaded the Hornady one because we couldnt find strelok.

It's wonky as heck. If you move the wind from RL to LR it changes the elevation adjustment drastically.

Chairgun elite on apple.

Your welcome.

 

[sndmn11]

Chairgun elite on apple.

Your welcome.

We shall give it a try!

 

[Megalodon]

My dad downloaded the Hornady one because we couldnt find strelok.

It's wonky as heck. If you move the wind from RL to LR it changes the elevation adjustment drastically.

That’s to be expected to some extent. Not sure what your wind speed was, but aerodynamic jump is an actual thing.

This just goes to show how different solvers address things differently and that it’s important to know what factors are turned on in the calculator you are using.

For the vast majority of public solvers, if you put good info in you’ll get good info out.

 

[mxgsfmdpx]

When getting a new baseline when I make a change or build a new rifle I use StrelokPro and compare to Bergers online calculator which I’ve found to be quite good compared to others.

I don’t even shoot Berger bullets I only shoot/hunt with hornady match and eldx bullets, but those two programs are usually within .1-.3 MIL of each other out to 1,000 yards.

Then it’s taking the old notebook out and confirming real world, repeatable hits at yardages, and I adjust my chart for that rifle/scope and cartridge.

 

[sndmn11]

That’s to be expected to some extent. Not sure what your wind speed was, but aerodynamic jump is an actual thing.

This just goes to show how different solvers address things differently and that it’s important to know what factors are turned on in the calculator you are using.

For the vast majority of public solvers, if you put good info in you’ll get good info out.

I'm ignorant to what that means. Does this seem correct?

R to L wind 15mph


L to R wind 15mph


No wind

 

[TxLite]

I'm ignorant to what that means. Does this seem correct?

R to L wind 15mph
View attachment 611256

L to R wind 15mph
View attachment 611257

No wind
View attachment 611258

Is there any chance the bullet spin is interacting with the wind and causing more/less drop?

 

[sndmn11]

Is there any chance the bullet spin is interacting with the wind and causing more/less drop?

I have that configured with 1:8 twist.


This is with 1:20 twist



So, the app's calculations are taking bullet spin and wind speed/direction to modify elevation.

I don't know if it's correct or not.

 

[TxLite]

I have that configured with 1:8 twist.


This is with 1:20 twist
View attachment 611278View attachment 611279View attachment 611280


So, the app's calculations are taking bullet spin and wind speed/direction to modify elevation.

I don't know if it's correct or not.

Very interesting. Wonder if the results would be mirrored with a LH vs RH twist

 

[sndmn11]

Very interesting. Wonder if the results would be mirrored with a LH vs RH twist

When I was playing with it yesterday I wondered the same, but couldn't find anywhere in the app to designate twist direction. If there was, I'd have leaned more towards it being correct. Since there wasn't, it made me assume there was some sort of error, and we wrote down the wind corrections from my strelok.

 

[DenimChicken]

For some weird reason, the ballistic calculators im using all seem to have a kind of decent discrepancy on their calculations.

For pre-tense, im shooting a federal power-shok copper .308 150gr out of a 24" 1:10R twist remington 700.

I am using 3 Ballistic Calculators, MD Ballistics (Mobile), Hornady (Mobile), and Vortex (Web based).

I'm not a computer, or a physics guy, so can't explain the why, only echo that I've had the same results. I have just accepted that they have different algorithms or formulas. I understand your frustration, and will say it's imperative to confirm your dope rather than blindly trusting the app. I have also found the better the data in, the better the data out. All that being said, same data in has resulted in almost 1 MOA differences at 600+ yards between several of the apps. Again, use apps as reference, and confirm with live fire.

 

[def90]

My dad downloaded the Hornady one because we couldnt find strelok.

It's wonky as heck. If you move the wind from RL to LR it changes the elevation adjustment drastically.

Bullets spin, my guess is that if you have a cross wind the bullet is either climbing in to the wind or descending with the wind.

 

[def90]

Very interesting. Wonder if the results would be mirrored with a LH vs RH twist

Pretty much all barrels have right hand twists. The Brits used to make barrels with left hand twist as they thought the left hand twist would compensate for a right handed shooters tendency to pull to the right.