And that's good but as you see, none of them actually EXPLAIN the dynamics of the physics involved...none explain HOW or WHAT is the actual activity that occurs, which produces a full choke effect in spite of the last thing that happens to the shot charge which is to exit a muzzle that is still wide open cylinder bore dimension.
I've wondered if it's a simple as this:
The gunsmith said that the outer layers of shot expand and start to slow down when the column enters the expansion chamber and that the central mass continues on forward at regular speed, and begins to get ahead of the slower shot.
To me, if that happens, then when the expansion chamber's tapered cone forces the outer layers of slower shot back down to cylinder bore size, the shot is being merged into the rear of the main centralized shot charge before muzzle exit.
He made a statement that this "makes the shot "squirt" out of the muzzle like a fire hose"...an interesting statement but still not clear on how that makes a tighter pattern...but, after rattling this around in my head the one thing I keep coming back to is this:
As the slower shot goes through the tapered forcing cone from the expansion chamber to cylinder bore size again, it has to accelerate and at the same time is getting jammed into/onto the rear of the central shot charge core as it's passing by...and makes for a longer shot string...less pellets in the front to veer off opening up the pattern, more shot strung out behind in the center line continuing along from behind making a tighter centralized pattern of shot at the target.
Dunno...just trying to figure out the HOW.
