UNDERSTANDING KILL PERCENTAGE
When our first version of the Shotgun Analyzer software was available, we demonstrated it to a number of shotgun owners with various levels of technical interest. Many shotgun enthusiasts don’t consider the manual methods of counting pellets and estimating pattern metrics because it is tedious, error-prone, and sometimes subjective – not an ideal process upon which to base decisions about your equipment and skills.
Our Shotgun Analyzer software and Turbo Targets change all this, making the process instant and accurate with objective results and meaningful data. Those who have regularly patterned guns immediately see the value in this solution because they have thought about what the pattern means and how to utilize the calculated results we provide for their unique situations – be it hunting or shooting sports at the range.
Many of these users quickly understand the calculations for point of impact, windage and elevation, and pellet count in a circle at a given distance, but then try to frame the results within the context of the multiple published opinions they have read regarding effectiveness of a pattern for their given application. This is the intended purpose of this whitepaper – to provide the reader with a better understanding of the basics of shotgun pattern kill percentage analysis, and how we express these calculations in our application. Kill percentage analysis can provide you with a comfortable pass or fail of a shotgun pattern that is specific to your sporting application.
Every time you pick up your shotgun to go hunting or shooting, you should be aware of your typical shot characteristics.=
1. What is the typical distance to your target? NRA standards for published choke performance are 40 yards. In practice, you may rarely shoot your target game or clays at that distance. We have provided a table below with guidelines for typical target distances for various game and situations. In your decision on distance, also consider locations and methods, such as decoying or pass shooting, thick woods or grass lands, or the multitude of trap and skeet contests. The distance you select is the distance at which you should shoot your pattern target.
2. How big is the Kill Size of your target? See the table below as a guideline. The Kill Size is the lethal portion of the game. For clays the table shows edge-on and full-on. Edge-on is shooting at the side view of the clay and full-on is shooting at the top or bottom of the clay. Use the software to run the numbers for both, it does not take long.
3. What size is the full pattern’s circle that you can expect your target’s lethal area to be within when the pellets get there? (Custom circle) Due to distance and movement of the target, the pattern circle of interest varies from 10 to 30 inches. Any more and your pattern will be too thin, much less and you should be shooting a slug. See the table as a guideline.
Kill Percentage Pattern Evaluation with Shotgun Analyzer
1. Shoot your targets
a. Select your load, choke, and pattern target distance.
b. For purposes of averaging, we recommend that you shoot at least three targets.
2. Photograph your targets and transfer the images to your computer. For best results, make sure your target is flat (no edge curls), and all four corner registration marks are clearly visible.
3. Launch Shotgun Analyzer, and click the “Open” button to load an image into the workspace.
4. Click the “Target Data” button to enter your session information, and then click the “Analyze Image” button to generate the basic processed data.
5. Now let’s perform a Killzone analysis on this pattern with parameters set for Mallard hunting. The Kill Table below gives us a Kill Size of 3- inches. We will evaluate our pattern within a 30-inch circle. Select the Custom Analysis button and enter a Custom Circle of 30, and Kill Size of 3. Click the OK button when you are done.
6. Check the “Killzone Analysis” checkbox on the left side of the application to show the results.
Understanding the Image Results
The purple color represents the gaps in the pattern that are big enough to miss a lethal area. The red color inside the purple regions is the center of the kill areas used to show the gaps. The red represents the kill percentage that was calculated. Champion skeet shooters want to see a kill percentage of 100%. If you see 98% (for example), you will kill 49 out of 50 birds that you properly point at. If you are at 100%, you can consider longer comfortable shots, larger shot size, or less choke.
When the application calculates a killzone map for a specified Analysis Circle, it overlays the Killzone Circle on the shotgun pattern at all locations where the Killzone Circle fits fully within the Analysis Circle. When there are no pellets found within the kill circle, we have found a killzone hole in our pattern where our game would survive.
When analyzing a 30-inch circle, you can miss your intended target by up to 13.5-inches and your Killzone Circle will still be fully contained in your 30-inch pattern.
Killzone Analysis and Shot Accuracy
It’s also interesting to note how shot accuracy affects the kill percent. We see more killzone “holes” in the pattern as our analysis location moves away from the pattern’s center of impact. This makes sense because the shotgun pattern spreads and creates larger gaps between pellets as you move away from the pattern center. Our 30-inch circle analysis yields a kill percent of 99.2%, and the circle size accommodates a shooting accuracy of +/- 13.5 inches from the target. As our shooting accuracy improves, so does our kill percent. Even moderate improvements in aiming skill improve our chances of a kill. For example, a 25-inch evaluation circle with accuracy of +/- 11 inches from the target yields a kill percent of 99.98% (pictured below). Our kill percent goes to 100% for a circle just under 18-inches.
We cannot stress enough that this table is a guideline. It is based on reference input from the studies of others along with some basic common sense that “this one is slightly smaller”. Each user should make their own decisions for shooting distance, choke selections and loads. As the distance increases, the choke should be tighter and the shot size larger. We are posting this in hopes that some readers will collaborate with us and point out accuracy issues or other improvements to make before we implement the table in the next version of our software. Feel free to email any discrepancies that you have as well as helpful reference links.