Every Shot Counts!
The Achilles heel of acoustic targets: If we see a digital number on a monitor, we ASSUME it’s correct? HEX Systems and the goBallistic web sites are the ONLY ones that offer copious target test documents revealing our STANDARDS.
Our STANDARDS are:
NO MISSED SHOTS. Acoustic sensors hear all sounds. If a target does NOT report a shot that hit the target, the target should be disqualified. It’s not “Take another shot”!
NO GHOST SHOTS. If a target monitor reports a shot that was NOT a Crossfire, then the system is flawed.
NO GROSS ERRORS. If there are MISSED SHOTS and/or GHOST Shots, then there are GROSS ERRORS. That’s where the Point of Impact in reported in error. The ONLY way to decipher that is through a test as described below.
Precision testing of all acoustic targets is a must. When goBallistic demo’s targets, or installs them, we will do an objective test at differing distances, and hopefully with a cross wind. When we leave you will have visual proof that the HEXTA Match-Grade target will perform to ours, and your satisfaction.
How to analyse the precision of an acoustic target.
These steps are links in a chain. Follow these steps!
There needs to be sufficient data per target, to be statistically relevant. Testing needs to be done at several distances in typical shooting environment. We recommend 300 yards, 600 yards, and 1000 yards. Or say 400 yards, 7oo yards and 1000 yards. Preferably with a side wind. If these is no wind do a test with significant offset. That’s easiest done at a shorted distance.
- Identify the acoustic center of the target.
- Identify the horizontal and vertical quarter lines, crossing through the acoustic center.
- Super-impose an aiming mark with the “dead center”, over the acoustic center, while squaring it’s horizontal and vertical lines with the E-Target lines. Using a piece of corflute is ideal, as it partially closes behind the bullet making measuring much more accurate. Sometimes best from the exit side.
- This is best done with four sets of eyes and hands.
- Shoot 15 rounds scattered around the target as evenly as possible. From center to outer edge. And in all 4 quadrants.
- With a steel ruler (in mm) carefully measure the center of POI holes, in the X & Y co-ordinates.
- Enter the actual measurements, and the computer generated co-ordinates, in the downloadable spreadsheet.
- Download E-Target Test
- Then compare actual numbers with computer generated results.
- You must repeat test at several distances i.e. 400 yards and 1000 yards, and additionally with a significant cross wind.
ANY shots that are NOT recorded, but landed on the aiming mark, disqualify the target as useable for Match “for the record” competition.
This is just one sample of a test we did at Ben Avery. It was overseen by an engineer, who also did the shooting.
These results are correlated with Australian Queensland Rifle association, which conducted the same tests on HEXTA targets as well.
Test results published on HEX Systems web site.
OPEN FACED TARGET TEST
Cross Wind Test on E-Target.
Gone with the wind.
Practical test on the effects of crosswinds on the shot position determination when sensors are open to environment.
During research and development of advanced shot determination algorithms, we had an opportunity to conduct additional tests. These tests allowed us to acquire additional practical data to back-up previously published theoretical research concerning shot position determination errors due to Doppler Effect when sensors are in an open environment with the potential to be affected by wind.
We set up a standard 8 sensor HEXTA target frame for the test. For the wind test the front corflute and the underlying rubber face were removed. This allowed the external environment to access the shot sensing chamber which would normally be protected from any external influences.
Two identical tests were conducted, each consisting of a string of 18 shots from exactly the same location. The first test was performed with calm wind conditions. The second test was performed with a simulated crosswind blowing across the target face from left to right. The wind was generated by an industrial pedestal fan located approximately 5M from the left-hand edge of the target. A wind indicator (similar to a flag) was located nearby the left-hand edge of the target to give an indication of the wind strength.
The shot impact points were monitored to ensure they were at exactly the same location at all times. The shot strings were performed with a maximum impact position variation of 1mm.
The test set-up server captured each individual shot’s details for each string. The results were analysed using our specialised test equipment and the details for each string of shots are shown below.
The example of the shot reported position without wind is shown in the left photo, and the reported position with the crosswind blowing, while the impact is in the same location as on the left picture, is shown in the right photo (note the wind indicators in the bottom left corners):
The shot examples show the response from all 8 sensors (56 shot location calculations). The error correction algorithm rejects the gross errors and brings the calculated point of impact to the most probable location for this situation. However, when a crosswind is present the vector of error has the same direction for all sensors and it is impossible to quantify or compensate for such an error.
The numerical results were analysed and are presented below:
The simulated wind from left to right across the target face has shifted the average group by 7mm to the right.
It can be seen on the shot plots that when the wind is blowing that there is also an increased uncertainty of the shot determination in addition to the shift of the group. The degree of uncertainty has increased from 0.34mm to 2.03mm with 2cm for the worst-case scenario.
Therefore, the total shot determination error detailed in the table shows a variation from -0.34 to 9mm in most cases as the wind speed varies to the level as shown by the wind indicator displayed on the shot plots.
Variations in projectile velocity will also affect the magnitude of described errors. Additional errors such as this plus the parallax error have not been taken into account during this test and are not shown on the pictures nor in the tables.
Precision for open faced target in a cross wind? Gone with the wind.
Accuracy testing of HEXTA and SMT electronic targets
© Daniel Consultants Pty Ltd 2017 Page 1 of 30
Accuracy testing of HEXTA and SMT electronic targets
Testing and report by Bruce Daniel, Daniel Consultants Pty Ltd
July 12, 2017.
Accuracy tests were performed on two brands of electronic target used in high power rifle / fullbore competition: (i) HEXTA-002 Match-Grade target (“HEXTA”), manufactured by HEX Systems Pty Ltd, Australia, and (ii) SMT model G2 (“SMT”), manufactured by Silver Mountain Targets, Canada.
The SMT target sensors were mounted directly to the front face of the HEXTA target. In this way both targets independently reported shot position for the same series of test shots (2 strings of 20 shots each). Both targets were operated in accordance with the manufacturers’ current user instructions. The SMT target was operated by the owners of the system, Bridgeville Gun and Pistol Club. Tests were performed at 1,000 yards using .308 projectiles. All shots were supersonic at the target. Tests were performed at Reade Range, Pennsylvania, USA, on June 1, 2017.
The HEXTA results showed very small errors, with standard deviations in the range 1.5 to 2.2 mm (0.06 to 0.087 in). There was no evidence of horizontal or vertical shifts, or radial bias. The results were consistent with results already published by HEX Systems and by independent parties.
The SMT results showed significant errors, with standard deviations in the range 9.2 to 50.1 mm (0.36 to 1.97 in). Significant horizontal and vertical shifts were evident, in the range 10 to 107 mm (0.4 to 4.2 in). Significant radial bias towards the centre of the target was evident: average 47 mm (1.86 in) in String #1 and 11 mm (0.45 in) in String #2. There is no other publicly available test data with which to compare the SMT results.
A glossary of terms is provided at the end of the document.