Fluid flow (shot pellets act as at least a semi-fluid) is one of the places where science and "horse sense" part company; one of the reasons it took so long to fly. I know perfectly well that it is easy to see in your mind's eye the shot getting "squeezed" through the choke and that causing higher pressure. If that were true, then airplanes would not fly/venturies would not have lowered pressure in the throat. When a fluid enters a constriction, it must flow faster to maintain mass flow rate. To flow faster, it must "use up" some of its pressure. Otherwise, energy would be created and it isn't. It is well proven that full choke adds at least an average of 40 fps to the shot as compared to cyl choke. That said, pressure is not a reason to change choke.
As for the bulge, if your "slight" is about the same as my "slight", there is only an aesthetic problem. The bulge area has been strained beyond the barrel steel's elastic limit, which translates into work hardened. Odds on, a knowledgable gunsmith can knock the bulge back into place; additional work hardening. Now, another gas hammer (the reason obstructions cause bulges) exactly at the former bulge will have to have higher pressure to rebulge that spot. If the barrel were to be overpressured generally, say by a high pressure shell, the first place to fail (weakest spot) would be at a different spot than the former bulge.
I know the above doesn't meet the "horse sense" test, but is science. I'll be happy to discuss if anyone disagrees or doesn't understand.
Last edited by Rocketman; 11/21/11 05:19 PM.
