cb-625 Calibration
Calibrating a cb-625

We promise 1% accuracy on the velocity and test them to half a percent to make sure they can do it.

If you want yours to agree with another chronoscope you can adjust a Mk3 or Mk4 cb-625 1% faster or slower by pressing buttons.

Hold RST down for 11 seconds until you see the 3 digit calibration number then let go. Usually set 100 for no calibration, make it 000 will make the cb-625 read 1% faster, setting it to 199 will make it read 1% slower. If you want it to read half a percent faster set it 50 and so on. Increasing the calibration number increases the time, hence the lower speed.

If you have a problem with the maths here is a handy calculator to do it for you.

My chronoscope reads velocity
I want it to read velocity
Suggested calibration value100

Calibration number
Did your chronoscope come with a test reference number written on the back in pencil?

Use it to access details of the 3 shot test it had to pass and get a suggested calibration number.


Overtype any value and press the calculate button.
Select the line you want to calculate using the radio buttons on the right.
 ft/s  m/s Find velocity
 ft.lbf  Joules Find power
 grains  grams Find weight