Precision Calculator Features:
- Calculates: group center, maximum group spread (CTC), group mean radius, group width and height, and group offset from point of aim.
- Standard or metric measurement display and data output. Angular units can be selected for Minutes Of Angle (MOA) or milliradians (mil).
- Controls have predefined values for common target distances and bullet hole sizes. Custom values can be entered by the user.
- All project information, including the target graphic, is saved in the project file. Files can be shared between users without recalibration or adjustment.
- Target project can be printed, all information shown in the main view is printed. A separate target data printout is available that includes individual group details.
- OnTarget v2.25 can open .tgx file created by all previous versions of the program. Note: OnTarget v2.25 project files cannot be opened in the the free version of OnTarget v1.10.
- Bullet holes can be selected and edited directly. No need to start over with the group if you slightly misplace a hole.
- Integrated scanner support using Microsoft’s WIA (Windows Image Acquisition) system.
- Target image can be rotated in 90 degree increments to correct orientation.
- Imports and saves popular graphic file types. (.jpg .bmp, .tif, .png)
- Group text and notes displayed in the Target View, in saved graphics, and on printed targets.
- Graphic elements for maximum spread, group extents, and mean group radius are displayed in the Target View.
- Graphic ruler for measuring distances in the Target View. The ruler is correctly scaled regardless of zoom level or target image source.
- Easy to use “Set Reference” command for defining a known distance on the target for correct scaling of calculations.
- Popup menu in the Target View for frequently used commands.
- Numerous hotkey combination for frequently used commands. (Go to the Help/Help Topics menu for more information.)
- Download or Purchase the OnTarget Precision Calculator.
- TDS includes all of the features found in the OnTarget Precision Calculator.
- Using the custom TDS targets, target center and bullet holes are located automatically.
- Hole Finder tool can add holes with a single click of the mouse.
- Virtual group data is generated. This includes: maximum center-to-center, offset from point-of-aim, mean radius, standard deviations, and CEP (Circular Error Probable) calculations.
- Target data can be exported to a Microsoft Excel compatible file for further manipulation.
- Point data import function combines several groups into one virtual group for more in depth and accurate analysis.
- Simulated ARA, PSL, and WRABF scoring from practice targets.
- Calculates the offset to best score for ARA, PSL, and WRABF targets.
- Target orientation setting in 90 degree increments.
- Automatic or manual entry of groups and bullet holes.
- Prints custom targets on 8.5" x 11.0" or A4 paper.
- Keyboard hotkeys for common operations.
- Download or Purchase OnTarget TDS.
Precision Calculator Quick Start
This short series of steps will get you started using OnTarget.
- Download the latest copy of OnTarget Precision Calculator.
- Run Setup.exe to install the program on your computer.
- Double click on the OnTarget icon to start the program.
- Open or scan an image. This will automatically create a new project.
- If the image is from a digital camera you should set the reference distance. This will insure that all measurements and hole sizes are correct. Scanned images should have the reference distance set correctly.
- Enter the target distance for the project. Many common ranges are listed in the Target Distance combo box.
- Enter the correct hole size for the holes in the target. Many common bullets sizes are listed in the hole size combo box.
- Zoom in on the portion of the target that has the group of bullet holes you want to work with. We'll do the other groups in a minute.
- Click on the Point Of Aim tool. Place the cursor over the target aim point and click to set the aim point position
- Click on the Enter Holes tool. The cursor will change to show that it is ready to define holes.
- Left click your mouse in over the target and the cursor will change to a circle that is scaled for the bullet hole size. Position the circle over a hole and click the left mouse button.
- Keep entering holes until you have finished the group. If you want to enter another group in the same project click on the new group button and start entering holes. To delete a group from the project select the group in the list and click on the Delete Group button.
- You can enter other information such as: ammo type, notes, location, etc... in the fields provided in the Group Info and Target Info tabs.
- To save the project click on the save toolbar button or go to File / Save. Use the File Save As dialog to select a location and name for the file then click OK.
- To save the entire project or the current view of the target as a graphic file go to the File menu and select the appropriate menu item. Use the File Save As dialog to select a location, file name, and file type, then click OK to save the graphic.
If you'd like to see how easy it is to get started measuring groups with OnTarget watch this short OnTarget Demo Video.
Please let us know if you found this guide helpful. More detailed information can be found in the help system that is installed along with the OnTarget program.
Measuring Group Size
There are several methods for measuring and calculating the size of a group of bullet holes in a target. These methods vary depending on the tools and equipment available but the goal is always the same; determine the center points of two or more holes in a target. Once you know the position of the holes center points, the group information can be calculated very easily.
The two most common methods of measuring bullet hole groups involve the use of calipers. Both methods are used to calculate the maximum spread, or max center-to-center distance, of the group. Let’s take a quick look at each.
In the first method a standard set of calipers is used to measure the extreme distance to the outside edges of the holes in the group. Then several holes are measured and an average size calculated. Finally the average hole size is subtracted from the overall measurement resulting in the group center-to-center distance.
The second method of measurement uses a set of calipers modified to hold a pair of clear circular templates along with an eyepiece for optical magnification. The operator looks through the eyepiece, aligns the two circles with the extreme holes of the group, and reads the center-to-center distance directly from the caliper.
With practice both methods can produce very accurate results and be done rather quickly. The first method is more commonly used because it can be done with a standard set of calipers. The second is used to certify groups because if its greater accuracy.
OnTarget uses the center of the bullet holes, regardless of caliber, to calculate the group information. The size of holes in a target will vary depending on several factors including, bullet construction, velocity, and target material. Basing calculations on the center of the hole eliminates error due these variances in hole size.
To measure a group, first an image of the target is imported or scanned. The bullet hole size is set, along with the target distance, the point of aim, and the reference distance if needed. The user zooms in on the bullet holes, selects the hole input tool and clicks in the Target View. A circle, drawn using the defined bullet hole size, is displayed and moves with the mouse. The user positions the circle over a bullet hole and clicks the left mouse button to anchor the shot. As each shot is entered the group information is calculated and displayed.
The circle shown on top of the target image helps to accurately position the center point of the hole. Zooming in on the group, and even individual holes, provides for very fine adjustment of the hole position. At maximum zoom levels you can easily distinguish individual holes in the tightest groups. Because all calculations are done using the center of the hole, accurate positioning becomes very important as group sizes shrink. Even if the bullet hole does not have a clean edge all the way around the circle can be positioned very accurately.
When measurements are complete, the target information can be saved to an OnTarget .tgx project file as a permanent record. Group information and point data can be printed out, or exported to an Excel compatible .csv file.