....Because of the recoil the gun and thus the right barrel rotate to the right, approximately around the buttplate. As the barrel is rotating to the right the shot charge is coming down the barrel. Just as the shot charge exits the muzzle it is headed parallel and a little to the right of the line the rib was on before Joe pulled the trigger. The shot, except for vertical curve, goes straight to the dove....
I don't believe it's possible to say this is so. Purely on science, if the gun rotates while the shot is in the barrel a lateral force is being applied. It's not likely to exit 'straight' out of the muzzle when it clears the gun. It's supposed to continue on a tangent to the diameter of the circle the gun was rotating on when the shot exited.
I don't believe the buttplate can be taken as the center of rotation, because it is not fixed and the shot is accelerating. I'd bet the radius that the shot is rotating on increases rapidly until leaves the barrel. One way to look at it might be the recommendation to follow through or swing through a moving target. It can be more difficult pick a lead then spot shoot at it with a fixed gun.
Say I shoot a thirty inch 100% pattern, any distance, then five more shots three from each barrel. The composite measures 32 inches. I'd want to do the back flips, but now I'm to conclude that the barrels are two inches out of regulation.
