The lead for the mover is calculated in increments of 5 degree.The equilateral triangle described at the 10 yard firing point, and half the 60 feet distance of the mover is the basis for the extrapolation of the Angular Coefficients. You need to remember the distance the bullet has to travel to the target is variable, depending upon the angle. All I have done is taken an average value. The worst error is at the closest distance, where the target is biggest! Constant bullet velocity has been assumed.

As I said, this calculates the required lead from the center position to an edge, I.E. half of the mover footprint. The other half is a mirror.
Mover speed is deduced from the target covering 60 feet in 6 seconds.