Cylinder bore is supposed to have a 0.000 constriction; is that the same as taper?
That's what I'm talking about.
The area in the bore right after the chamber will be larger and taper will increase very slightly as the shot goes down the barrel. Obviously a full choke will have the most taper and a regular cylinder bore will have the least taper.
So if you think of a shotgun barrel as a VERY SLIGHT funnel, if you hack off the barrel at a point where the taper isn't ideal, your shot pattern will open up too fast.
I could be wrong about all of this and the bore constriction may be exactly the same all the way down the barrel but this is what I assumed to be true.