AusVarmint

I have had my Doppler LabRadar chronograph for nearly three years, the first in OZ. . It has allowed me to do a lot of things quickly which previously took a lot of time and effort shuffling one or two Chronys about and checking calibrations. Been wanting to do this for some time so .... yesterday.

LabRadar and Chrony F1 go head to head.
What  velocity correlation might we expect from these two chronographs when shot together and what general conclusions may be drawn?

 At a tape measured distance of 14 yards/42 ft muzzle to mid point between the Chrony sensors, I shot 10 shots simultaneously over the Chrony and the LabRadar microphone trigger to get some conclusion as to relative reliability.  
The Labradar was set to record velocity at precisely 14 yards to the nearest one fps. (Note that the LR does record a number of velocities for every yard but can also have 5 user chosen yard or metre settings). Thus comparisons could be made.
14 yards was chosen as the longest range I could get for the Chrony with good sky screen access in my yard (no tree shadow etc).
The measure of default 12 inches between Chrony sensors was checked as best I could – see pic: ( if you have never checked yours, it is a good idea to do so).  It took some time to line everything up including a safe target at 25 yards. A laser pointer helped and Wendy, bless her, helped with the tape. The results were astonishing at least to me they were.

The rifle was my 16 yr old .22 Excalibre/FX 2000 air rifle which has no regulator but has shot over 70 sub inch 100 yd 5 shot groups.
It was choked back with its transfer port adjustment screw to shoot under 12 fpe, with 15.9 gr JSBs , allowing just enough noise to trigger the LR microphone.

Raw data:
Chrony  then  LR  same shot at 14 yards.
534.2 fps  535 fps
530.2         531
538.1         538
540.2.        540
535            535
536.8         537
538.8         539
539.3         540
537.5         538
534.2         535

Averages
536.43      536.8
Highest
540.2         540
Lowest
530.2         531

Well there is a morning’s work/play and the results are most satisfactory.  The LR cost me US $ 550 plus exorbitant US freight charges almost three years ago.  It was the first into OZ  but they are now available here. It does so many things for me.
I hope you enjoyed the read ….  Kind regards, Harry.

That's an excellent write up.

It always intrigues me how 'calibrated' our various measuring devices are, particularly when you have more than one device.

You must be happy to determine that both devices produce comparatively consistent results.

Very consistent velocities out of that rifle Harry.

The Raven: Thank you; and yes it is always good to see instruments concur and when they are priced so far apart - especially so. Whenever comparisons are implied between studies it is imperative. That is why we have lab test protocols, and when it really matters, test teams visiting labs around the world correlating instruments to standard values. Of course the Chrony can't do all that the LB can do but for most shooters an indication of mv or its variation is all they want.

Missed: That unregulated Excalibre has given some very impressive and consistent shot strings.
Here is a 34 shot string with just 10 fps spread at 850 fps JSB 15.9 gr Exacts from a 190 bar fill of the just 203 cc reservour tube. You should be able to expand the picture to see just how consistent it was. All that from a rifle that was designed 20 years ago.
Best regards, Harry.