Group Size Calculator - V2.4
-- now supports metric measurements --
||If you have access to a scanner, you can scan your targets into a
"*.bmp", "*.jpg", or "*.gif" file then open this file with the GSC program. Then, simply by left-clicking
when the cursor is centered on top of each bullet hole, the X-Y coordinates are
measured. The GSC allows you to calibrate your scanner and display such that
at maximum resolution accuracy to +/- 0.001 inch is possible. To measure
accurately you must calibrate your scanner / monitor. This calibration
is only available in the registered version.
||Without a scanner, you are still able to use the GSC to calculate
your group statistics. Using a good caliper, measure the X and Y coordinates
of each shot and place them in a text file. Then open this file with the GSC.
One can also hold a target up to the monitor and position the cursor underneath
each bullet hole and click - this is less accurate due to parallax, but with
practice can suffice. The monitor still needs to be calibrated - one can
hold a ruler to the screen and use a method similar to that described in
Setting your magic number. In addition, the
GSC scanning window needs to be sized such that it encompasses the desired
portion of the target.
||Using either of the capture methods above, the GSC then displays
a representation of your target. If you so choose, you can elect to remove any
of the shots from the group calculations (e.g. in the case of a known flier).
||The GSC then calculates the following statistics for your group:
A User's Manual is available to help new users become familiar with the operation of
GSCalc and some instruction / insight regarding how to interpret and best make use
of the output from this program. This manual is available in either pdf or html format.
The manual references two additional files, one of which is used as an example, the second
which is of general use when scanning in targets. These are all available here:
User's Manual (pdf format,
Buy It Now
This program is shareware. Although you can download and try it out for free, to enable
calibration of your scanner/monitor you must obtain a registration code. You may either send
a check for $10.50 (US funds) to the address shown in the program (under the "Help" menu), or
use the PayPal link below. Note, please: this is an email only transaction, so I need to have
your Name and email address provided to me by PayPal - so please enter your information in
- V1.3 - this adds the ability to set any caliber of bullet to display. There has
also been some confusion as to the use of this caliber setting (it's only used for display
purposes and not for any group calculations). A help/clarification message has been added
as a reminder.
- V1.3.5 - this fixes a bug for Windows98 users. Due to some differences in
the way it initializes, some users were getting a "Divide by zero" exception. This
has been fixed.
- V1.4 - For registered users, this version now remembers your previous
choice of cursor, window sizes/locations, and the directory you save your images in.
- V1.5 - This fixes some bugs introduced in V1.4 for registered users. Setting the
magic number is now "cleaner" and the occassional "error 62" has been (hopefully) eliminated.
- V1.6 - Another bug fix introduced in V1.4 - the program forgot how to remember your
magic number! I had to teach it how to remember again.
- V1.7 - The main window and the scanner window would not minimize - they do now. Also,
when no shots were entered into the scanner window the program would complain six times about
no shot file being opened (each subroutine would detect a divide by zero error) - it only
complains once now.
- V1.8 - Adds support of metric units of measure.
- V1.9 - Changes email contact information and adds a "recalculate and recenter" menu item
for easing use of .gsc files.
- V1.10 - Fixes some bugs introduced in V1.8 with the Metric / English interchange. Adds
the ability to re-zero groups (force the group center to (0, 0)). Allows one to embold the
image in order to get a stronger printout. The image also now automatically redraws itself
after any change in any parameter to ease use.
- V1.11 - Adds the ability to save the virtual target itself as a *.bmp. This also cleans
up the saved *.gsc files such that you no longer need to clean them up prior to reuse. After much
discussion with a GSCalc power user and statistian the Group Standard Deviation has been removed
as being not only irrelevant but misleading.
- V2.0 (3/2007) Some error codes that
appeared with Windows XP have been resolved. There has been some debate regarding the "best"
means of measuring group "goodness". One can read a discussion of
Average Radius being used as the best measure
and an arguement for the use of the Mean Average Deviation. Which to
use is left to the individual user. A couple
of useability features have been added:
- GIF and JPG target scans are now supported
- A "recalculate" button has been added for when fliers are manually identified.
- One can now temporarily set the scale on a scanned target independent of the
magic number. This allows one to obtain group statistics on a non-calibrated
scanned target. (available to registered users of the program only)
- V2.1 (9/2008) With the explosion of wide-screen monitors, many have unequal pixel spacing
in the horizontal and vertical directions. This version adds an option to have separate
horizontal and vertical Magic Numbers. Note, however, that these separate numbers apply
only to the scanning portion of the program, not to the re-display. This is to preserve
accurate proportioning when printing from the program. The scanned targets and resulting
group statistics will be more accurate with separate Magic Numbers, but, depending on
your display, the displayed target may appear a bit disproportionate.
- V2.2 (5/2010) Increases the number of shots that GSC will handle from a single target to 128.
The previous count had been 32.
- V2.3 (11/2010) Works around a problem encountered when trying to register GSC on a
Windows 7 (and Vista??) machine. Windows 7 views all files with the ".reg" file extension
to be registry files and blocks program access to these. GSC now uses a ".txt" file to
save registration information and user preferences.
- V2.4 (10/12) Ok, really increases the number of shots that GSC will handle to 128. With V2.2 one could scan more than 32, but when opening an old GSC file, the limit was still 32. Now fixed.
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