Daryl,
Thanks for posting this. I recall some data posted long ago on this, either from you or another LeFever owner.

It appears to me that these barrels were honed out by some partially hand operated method where the hone dwell and depth was controlled by operator input/movement. This would explain the somewhat irregular rate of taper. It also appears that there was a target diameter at approx 2" from the muzzle, then the choke.