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Applied Ballistics Analytics with WEZ!

This is a quick over view of AB Analytics. Their is a POD Cast that goes in to details on the benefits and use of WEZ. Their are also a couple of articles I will include for your reading. WEZ is also mentioned in the book Applied Ballistics for Long Range Shooting by Bryan Litz. This is avaliable in hard copy and ebook format. I will first include some links:

Understanding WEZ Analysis and Using it to increase Probability of Hit: http://www.nvisti.com/wp-content/uploads/2014/06/NVDOC14.02-WEZ.pdf

Using WEZ Analysis: www.appliedballisticsllc.com/Articles/ABDOC115_ProbabalisticWEZ.pdf

How External Ballistics Programs Work: http://www.appliedballisticsllc.com/Articles/ABDOC102_HowBallisticsProgramsWork.pdf

Problematic Weapon Employment Zone (WEZ): http://www.appliedballisticsllc.com/Articles/ABDOC115_ProbabalisticWEZ.pdf

You can find it here in the store(Note the book Accuracy Precision for Long Range Shooting comes with the purchase of the software) https://store.appliedballisticsllc.com/ProductDetails.asp?ProductCode=DL2001
This is an overview, not a how to. Their is a full instructional manual that comes with the software.

To see a video demonstration visit here:
http://www.abmediaresources.com/ABAnalytics.mp4

If you ever want to compare multiple bullets, or the same bullet out of multiple weapons. You can open up more than one version! Allowing you to change what you want to see how it affects your ballistic calculations!

When you first download it, you will be given an executable file. This file needs to be run, and then told where you want the folder to be placed. This does not install on your PC. The reason for this being that a number of users run it from Military Computers, which do not allow installation on the computer. So in order to allow the Military users full access its designed to run stand alone, and not installed on the computer.

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Weapons Profiles are saved in the Profiles Folder. This is true for the Profile Loader as well. This allows you to move them as needed. You can also create weapons profiles with our online ballistic calculator, then export them. These will also work here.
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When you first open it, this is what you will see:
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The best thing to do, with any new software is to check out the options. Here you can edit how it looks. Open a Profile Loader to upload to a kestrel. Save profiles you have created. Export Range Cards. Edit settings for Mil/MOA/Imperial/Metric Input and Output.

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Editing how the software visually looks
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Opening saved weapons profiles.
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Always check your units to make sure they line up with what you are doing:
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Once you start creating a profile, you will see that it has the entire custom library pre-loaded, as well as over 1000 G7 and G1 curves. If you select a new bullet, it will completely clear the data you have input in to the system, so you are starting from scratch each time you load a new bullet.
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If you select a bullet that is in the custom library, the G1/G7 and BC are grayed out, as its using the proprietary information from our ballistics laboratory, as seen here.
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These are the options you have. Muzzle Velocity Calibration using the True Drop of the bullet. Drop Scale Factor for Ballistic Calibration. Sight In Conditions for long range zero, Zero Offset, and Sight Scale Factor (Turret Calibration if the clicks are not exactly 1/8th or 1/4th MOA per click). Muzzle Velocity Temp Table, for calibrating MV shift with Temp Shift (This is a part of powder stability). Range Card Settings, allowing for you create a custom range card, and decide what intervals you want, down to 1 yard if you are doing a Danger Zone calculation.

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WEZ. Their is a lot that has been written on, and about how to use WEZ. So this is simply an overview of what you have, for more information on what you can do with it please reference the book, and materials above. One thing its really good for, is comparing bullets. A higher BC slower bullet can be a better choice than a lower BC faster bullet at times. A higher BC bullet can also make up for a poor performance (2MOA) rifle. This software is good at demonstrating this. You can the type and size of target to match your needs, be it military, competition, or hunting. The inputs that you use for WEZ need to be exacting of your ability. Bending or putting in better inputs than your capabilities can give a false sense. The other thing to note, is I use inputs based on if I am doing the reading of wind, or my Kestrel 4500 Applied Ballistic Units are doing it.

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Wind Analysis. This is a great tool. If you want to know exactly how the wind is affecting your shot, you can put in the exact winds at each point you are shooting. So if you have an updraft, a ravine, river, or whatever wind conditions you might be encountering. If you have zero wind the first 750 yards and then wind to the target from that point on, you can analyze how this will affect your shot.
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This is a great tool for the competitive shooter, hunters, and just anybody that wants to know how changing something will affect their shots. Its also a great tool for following along in the Applied Ballistics Library of resources. No more guessing, no more "well this works for me". Now you can get all the answers you want by doing different scientific analysis's.
 
Doc,

It looks like WEZ places shooter skill in the "rifle" category. Is that correct?

Also, I'm confused about accounting for the standard error in MV. Are you looking at the error of the chronograph, the variation in the actual MVs due to the reloading process, or both?

Finally, is it a simple matter to back out the MV variation to isolate the pure "rifle" error? These two things are sort of married together right?

Thanks,
-Joe
 
Joe Grad said:
Doc,

It looks like WEZ places shooter skill in the "rifle" category. Is that correct?

Also, I'm confused about accounting for the standard error in MV. Are you looking at the error of the chronograph, the variation in the actual MVs due to the reloading process, or both?

Finally, is it a simple matter to back out the MV variation to isolate the pure "rifle" error? These two things are sort of married together right?

Thanks,
-Joe

No, that is just a breakdown of what affected it most in that instance. The thing to note, is that I was using the accuracy of the Kestrel 4500 Applied Ballistics in that instance. Being able to call wind inside 5 or 2 mph is an experienced good shooter, you will see in the photos I have it set to .5 mph which if you can call wind in an unknown zone, on an unknown target with your first shot being at 1000 yards. Then your wind call is phenomenal. I had actually broken down the information in to the Kestrels ability. If those numbers were adjusted to my abilities and not the Kestrels it would be a completely different graph.

The MV error could be your error, or the chronographs. If your doing the MV by hand, because you don't have a chronograph. Or you can input the given tolerances or error of your chronograph. Or you can input the known error of your chronograph if you have had a chance to test for it and know what it is.

You can set any value to 0 and eliminate it.
 
Just a shot in the dark... If parallax error from a fixed objective scope was incorporated in the WEZ analysis, maybe the grouping anomalies Bryan is looking to test on the other thread can be simulated by running WEZ.

...Just an idea
 

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Doc,

I'm trying to understand the red dotted curve (attached). Is this the cumulative error as a percent of the sum of all vertical errors? If so, it seems like it starts a bit on the high side (80+ %). I would expect it to be closer to 50% (36in./72in). Same for the horizontal.


-Joe
 

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It helps to see what is more important vs what is less important to focus on. Don't take this as an option to ignore a factor, It just puts them in a precedence order.
 
The axis for the red line is on the right. It's the percentage of total uncertainty.

Starting from the left side and building across to the right, you see that the range uncertainty is like 85% of the total vertical uncertainty. Add pressure, and you're at like 96%, add MV and you're at 99%, etc. All other's combined take you from 99% to 100%.

It's just another way to quantify the dominant factors.

-Bryan
 
Right. So why is the cumulative (vertical) uncertainty for the range 85%? The total uncertainty in this example is about 72in, but the "range" portion is 36in. Shouldn't it be closer to 50%? See attached....

-Joe
 

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range is 50% of the total error, range + pressure is 75 percent of the total error, range + pressure + muzzle velocity is 90 percent of the total error. The red line is showing the cumulative error as you go from left to right.
 
Bryan,

I agree. I made that last graph in excel to illustrate an error in nVisti's WEZ literature.


Which chart is correct.... nVisti's or mine????
 

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The nVisti guys have reviewed this thread and will be commenting shortly. I understand the reasoning now, but rather than explaining myself, I'll let the guy who actually programmed it explain.

Good lesson to learn regarding WEZ. Thanks for asking the questions.

-Bryan
 
Hey Joe – good questions, and I can understand where you're coming from...

In order to get a system-level error number, the individual errors do not sum directly together, but rather can be treated as described in this section of the Propagation of Uncertainty page.
https://en.wikipedia.org/wiki/Propagation_of_uncertainty#Simplification

So the errors don't straight add together, they're added together using that equation, where f is the hitpoint, then x, y, z, etc are the individual components (MV, range, temp, pressure, etc). So we're taking each component, looking at how it affects the hitpoint, and then combining all the contributions to determine the total system uncertainty.

When you have one error that is large, the second error makes little contribution to the system error until it grows considerably.

Let's say you wipe out all the errors but range in that example graph. You'd still have about 88% of the total uncertainty at the system level. If you add in the pressure uncertainty, then the overall system uncertainty only grows a little bit from there. So these two errors account for about 97% of the uncertainty at the system level. The rest of them only contribute that last 3%.

That's the short version – let me know if you have additional questions

~Dan, nVisti
 
Dan,

Thanks for pointing this out. I went back to Bryan's book and found the chapter where he explains adding the component errors using RSS. It's not intuitive and certainly changes the way I think about how the uncertainty is weighted between variables.


Thanks Doc and Bryan for your patience on this one.

-Joe
 
The simple answer is you can neither average nor add either standard deviations or ranges (extreme spread). Variances (standard deviation squared) can be combined; but even in that case it is not always a simple, direct exercise. If you really want to know ad-nausea look up Components of Variance, which is a subset of the Analysis of Variance (ANOVA) procedure.
 

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