I believe that you're wrong, Rocketman. Pix of shot columns emerging from barrels show the center of the mass poking ahead, not a hole as your explanation (front of the shot column to the back of the column as it flows through the constriction) would anticipate. Also the choke effect is opposite of your view ( Thus, the pellets subject to more choke effect will have lower "sideways" velocities and will take longer to disperse compared to less choke effect) as the radial acceleration toward the bore center imparted to the shot is speed and constriction dependent - more of either making more choke effect. I find it difficult to accept that the air in the shot mass has any effect even in the least.
did you read what you had written before you posted it?

Dr.WtS
Mysteries of the Cosmos Unlocked
available by subscription