Originally Posted By: L. Brown
Don, I can't find photos in Brister's book to support my point, but I think Brister shot enough targets to have detected a difference in how full performs (in terms of how rapidly it opens) compared to IC (or chokes more open than that). Here's a quote from his book:

"The full choke's reign of superiority is considerably shorter in useful yards than IC's . . . By 55 yards, with ordinary hunting loads, the full choke has become less efficient than the IC as 40 . . . So what we have here is one choke that is quite deadly for a distance of about 18 yards (from 20 to about 38 with most hunting loads in a 12 gauge) and another that shines for 10 yards or so with the same ordinary load."

Larry, my point is that patterns behave in an orderly way without sudden changes in diameter and always with a Rayleigh distribution (nicely approximated by a normal distribution). The swept volume is a trumpet, instead of a cone, because the pellets loose forward velocity faster than they loose sideways velocity. Choke effect delays pattern bloom and, over the envelope of useful choke values, increases shotgun effective range by some 50% to 100%, depending on point of view.

DDA