To check the velocity at which a paintball marker is firing, a chronograph is used. The radar chronograph uses a small Doppler radar to measure the velocity of the paintball.

The paintball is fired over the machine. The radar picks up the paintball and records the speed of the ball on a digital display.

If the marker is firing paintballs at over 300fps, it is adjusted to lower the velocity.

The first chronograpghs used light. The paintball was also fired over the machine. Light entering the machine was broken, starting a timer. The machine measured the time the light was broken and calculated the velocity of the paintball.