Have I got this right?
A group of 4 bw in 2 ranks can shoot at a Sp. The factors are 3 for the 1st shooter, +1 for the 2nd shooter in the rear rank aiding the primary shooter, -1 to the Sp for the 3rd shooter aiding, and the 4th shooter doesn't come into it. Final factors 4 (bw) vs 3 (sp)
