As far as I know it works with the equation Distance = Rate times Time (D=R*T). There is a sensor at the front of the crony, and at the back. When the bullet passes the front sensor the crony begins to time how long it takes to reach the back sensor (when the bullet passes the sensors it breaks a light beam.) That number is equal to T or time. The distance between the sensors equals D or distance. The crony plugs these numbers into the equation D/T=R, and figures out the R or velocity for that bullet. I hope this helps. Good luck.

Edited by - handloader1 on 02/14/2002 00:16:35