Originally Posted By: Geno
Gas dynamics. The gas pressure will be increasing dramatically just behind shot column and wads, if shot column and wads meet obstacle such as full choke for example and slow down.


I agree with Geno mostly. I don't think a full choke will act as an obstruction, but increasing constriction may make shot bridging more likely. When the shot column first enters the choke section, the shot has no idea what the constriction will be. So, if the shot column was going to react to the constriction as if the constriction were an obstruction, the taper angle would be the important factor; short chokes would be more prone to bulges than would long choke sections. Since the shot flows through the choke, even full, without damage a vast majority of shots, bulging is a rare event. Shot bridring also seems a rare event. However, a shot bridge will support shear force and could, therefore, slow some of the shot column and the wad which could incite a gas hammer. IMO