As part of a large series of chronograph comparisons, I conducted this week a test to determine the influence of mounting doppler radar chronographs to the rifle vs. to static mounts beside the rifle, like the supplied tripods.
Experiment Overview: Gun Mount vs. Static (Tripod) Velocity Readings:
Many shooters have questioned whether the Mini-Doppler Radar units present different readings when rifle-mounted vs. mounted in static positions, such as the supplied tripods alongside the rifle. In this experiment, I mounted 3 chronographs to the rifle, with matching units on a static rack beside the rifle, fired 30 rounds, then swapped the units from rack to rifle and rifle to rack. In theory, because the rifle is moving rearward in recoil, mounting these mini Doppler Radar chronographs to the rifle should produce slightly higher velocity readings than when using the units on static mounts beside the rifle. This experiment was intended to capture and demonstrate this potential offset in speed read by gun mounted vs. static mounted units.
Aspects of Comparison:
The rifle used for this test was a Defiance Deviant Elite Short Action, Bartlein barrel 26" 1:7.5" twist chambered in 6 Dasher with SilencerCo Omega, firing handloaded ammunition:
Berger 105 Hybrid 6mm
Hydroformed Lapua 6 BR brass --> 6 Dasher (>15 firings)
30.5gr Varget
CCI BR4 Small Rifle Benchrest Primer
This comparison was made using the same 6 chronographs of 3 models:
Results of Comparison:
For ease of visualization, I applied a heat map to the data captured from the 2 units of each brand, and compared the velocity readings for 30 rounds (less read failures). In the majority of readings, the gun-mounted unit detected higher velocity than the static mounted unit.
The Garmin mounted to the rifle during the first string produced readings which averaged 4.5fps faster than the Garmin mounted on the static rack, and exhibited the faster speed 20 out of 27 readings. The Athlon mounted to the rifle read the higher velocity than the static-mounted Athlon in 20 of the 30 readings, and averaged 2.4fps faster than the Athlon on the static rack.
Following the first string, the units were swapped from the static mount to the gun and vice versa, and the same results persisted - the gun mounted units registered faster speeds for the majority of shots than the unit mounted on the static rack. Swapping the position of the units, the velocity offset also swapped. The Gun Mounted units again displayed the faster velocity than the static mounted units from each brand, again visibly represented here by the red/green heat map. For each, individual shot, the faster reading between each brand (green) was registered by the gun-mounted unit, faster than the static mounted unit.
In 27 of the 30 shots, the Gun Mounted Garmin registered the faster speed than the Static mounted Garmin, averaging 3.3fps faster. In 22 of the 30 shots (one tie), the Gun Mounted Athlon unit registered the faster speed than the Static Mounted Athlon, averaging 3.9fps faster than the static unit.
Further visualizing these trends by plotting the velocity readings for each unit, we can see the faster trend for the gun mounted unit over the static mounted unit, and can see the swap in the trend for each unit when they are swapped between the rifle mount and static mount.
Depicted here are the trends for each Garmin unit - Garmin 1 started the experiment on the static rack with Garmin 2 on the rifle (actually Garmin 3); during this phase, Garmin 2 read the faster speed as mounted on the rifle than Garmin 1, which was mounted on the rack. When swapping Garmin 1 onto the rifle and Garmin 2 (3) onto the rack, the trends swapped and the gun mounted unit again rose to the top of the trends.
This was also observed for the Athlon units. Athlon 1 was mounted to the rifle for the first half of this test, depicted in the dark green line, which carried (predominantly) above the static mounted Athlon 2. When swapping the two units, moving Athlon 2 to the gun and Athlon 1 to the static mount, the Athlon 2 shifted to the higher velocity over Athlon 1, trading the teal line above the dark green line.
Conclusions of Comparison:
One conclusion drawn from this experiment was that a replication may be pertinent, both to improve the data capture quality as well as improve the conclusions drawn regarding the offsets registered by each unit. On this specific event, I had difficulty with capturing the shots with the LabRadar LX's, losing over half of the data opportunity by missed shots by both units. I also recognized a weakness in this particular execution, as I changed one of my Garmin units, meaning the standard for offset and potential error between my previous 2 Garmin units may not apply for this new unit, so in subsequent replication of this testing, I should fire a baseline string to establish the expected offset and magnitude of differentiation between the two units: In other words, repeating this test, I would fire 25-30 rounds with the units both mounted in my static fixture, then remove one of each unit and mount it to the rifle, and then in a 3rd phase, swap the units from gun to static and static to gun (static:static, Gun:static, static:gun) rather than ONLY testing with the units split between static and gun mounted.
After this direct experimentation, I consider the hypothesis that gun-mounting mini doppler radar chronographs will produce readings of higher velocity than using the chronographs mounted on their supplied tripods or other static mounts off of the gun to be confirmed. The offset for this load and rifle was approximately 3.5fps faster reading for the gun mounted unit over the static unit.
In this experiment, the average difference to be expected (not corrected for inherent unit-to-unit variability) was demonstrated to be between 2.4 and 4.5fps, with an average of 3.5fps. In other experiments, described above in this thread, two Garmin units demonstrated an average difference of ~1fps for this ammunition lot, never exceeding 2.8fps, whereas in this test, the differences between rifle mount vs. static mount were 2.4 and 4.5fps - such the difference between two units is demonstrated to be notably smaller than the difference between the gun mounted vs. static mounted units in this experiment. But additional testing should be replicated to confirm this offset for the new Garmin unit I'm using as well as establish a baseline offset for the specific experimental session.
Experiment Overview: Gun Mount vs. Static (Tripod) Velocity Readings:
Many shooters have questioned whether the Mini-Doppler Radar units present different readings when rifle-mounted vs. mounted in static positions, such as the supplied tripods alongside the rifle. In this experiment, I mounted 3 chronographs to the rifle, with matching units on a static rack beside the rifle, fired 30 rounds, then swapped the units from rack to rifle and rifle to rack. In theory, because the rifle is moving rearward in recoil, mounting these mini Doppler Radar chronographs to the rifle should produce slightly higher velocity readings than when using the units on static mounts beside the rifle. This experiment was intended to capture and demonstrate this potential offset in speed read by gun mounted vs. static mounted units.
Aspects of Comparison:
The rifle used for this test was a Defiance Deviant Elite Short Action, Bartlein barrel 26" 1:7.5" twist chambered in 6 Dasher with SilencerCo Omega, firing handloaded ammunition:
Berger 105 Hybrid 6mm
Hydroformed Lapua 6 BR brass --> 6 Dasher (>15 firings)
30.5gr Varget
CCI BR4 Small Rifle Benchrest Primer
This comparison was made using the same 6 chronographs of 3 models:
- Garmin Xero C1 (x2 - noting, one of the Garmins used in this test is NOT the same unit as used in previous testing)
- LabRadar LX (x2)*
- Athlon Rangecraft Velocity Pro (x2)
Results of Comparison:
For ease of visualization, I applied a heat map to the data captured from the 2 units of each brand, and compared the velocity readings for 30 rounds (less read failures). In the majority of readings, the gun-mounted unit detected higher velocity than the static mounted unit.
The Garmin mounted to the rifle during the first string produced readings which averaged 4.5fps faster than the Garmin mounted on the static rack, and exhibited the faster speed 20 out of 27 readings. The Athlon mounted to the rifle read the higher velocity than the static-mounted Athlon in 20 of the 30 readings, and averaged 2.4fps faster than the Athlon on the static rack.
Following the first string, the units were swapped from the static mount to the gun and vice versa, and the same results persisted - the gun mounted units registered faster speeds for the majority of shots than the unit mounted on the static rack. Swapping the position of the units, the velocity offset also swapped. The Gun Mounted units again displayed the faster velocity than the static mounted units from each brand, again visibly represented here by the red/green heat map. For each, individual shot, the faster reading between each brand (green) was registered by the gun-mounted unit, faster than the static mounted unit.
In 27 of the 30 shots, the Gun Mounted Garmin registered the faster speed than the Static mounted Garmin, averaging 3.3fps faster. In 22 of the 30 shots (one tie), the Gun Mounted Athlon unit registered the faster speed than the Static Mounted Athlon, averaging 3.9fps faster than the static unit.
Further visualizing these trends by plotting the velocity readings for each unit, we can see the faster trend for the gun mounted unit over the static mounted unit, and can see the swap in the trend for each unit when they are swapped between the rifle mount and static mount.
Depicted here are the trends for each Garmin unit - Garmin 1 started the experiment on the static rack with Garmin 2 on the rifle (actually Garmin 3); during this phase, Garmin 2 read the faster speed as mounted on the rifle than Garmin 1, which was mounted on the rack. When swapping Garmin 1 onto the rifle and Garmin 2 (3) onto the rack, the trends swapped and the gun mounted unit again rose to the top of the trends.
This was also observed for the Athlon units. Athlon 1 was mounted to the rifle for the first half of this test, depicted in the dark green line, which carried (predominantly) above the static mounted Athlon 2. When swapping the two units, moving Athlon 2 to the gun and Athlon 1 to the static mount, the Athlon 2 shifted to the higher velocity over Athlon 1, trading the teal line above the dark green line.
Conclusions of Comparison:
One conclusion drawn from this experiment was that a replication may be pertinent, both to improve the data capture quality as well as improve the conclusions drawn regarding the offsets registered by each unit. On this specific event, I had difficulty with capturing the shots with the LabRadar LX's, losing over half of the data opportunity by missed shots by both units. I also recognized a weakness in this particular execution, as I changed one of my Garmin units, meaning the standard for offset and potential error between my previous 2 Garmin units may not apply for this new unit, so in subsequent replication of this testing, I should fire a baseline string to establish the expected offset and magnitude of differentiation between the two units: In other words, repeating this test, I would fire 25-30 rounds with the units both mounted in my static fixture, then remove one of each unit and mount it to the rifle, and then in a 3rd phase, swap the units from gun to static and static to gun (static:static, Gun:static, static:gun) rather than ONLY testing with the units split between static and gun mounted.
After this direct experimentation, I consider the hypothesis that gun-mounting mini doppler radar chronographs will produce readings of higher velocity than using the chronographs mounted on their supplied tripods or other static mounts off of the gun to be confirmed. The offset for this load and rifle was approximately 3.5fps faster reading for the gun mounted unit over the static unit.
In this experiment, the average difference to be expected (not corrected for inherent unit-to-unit variability) was demonstrated to be between 2.4 and 4.5fps, with an average of 3.5fps. In other experiments, described above in this thread, two Garmin units demonstrated an average difference of ~1fps for this ammunition lot, never exceeding 2.8fps, whereas in this test, the differences between rifle mount vs. static mount were 2.4 and 4.5fps - such the difference between two units is demonstrated to be notably smaller than the difference between the gun mounted vs. static mounted units in this experiment. But additional testing should be replicated to confirm this offset for the new Garmin unit I'm using as well as establish a baseline offset for the specific experimental session.
