I wonder why the swing velocity of the shotgun (shotgun "lead") wasn't entered in the calculation. There are three, not simply the two movements (speed of shot towards duck and duck's speed), in play in a crossing shot. The gun barrel is in motion to lead the duck and the crossing momentum of the shot column would be losing velocity (as does the shot's muzzle velocity). Perhaps the calculation of the shot column's sideway's velocity is minor by the time it arrives at the 40 yard duck. (Once an object is in motion it will continue to stay in motion until slowed and stopped by gravity and friction.) Gil
