I will not argue the point that "Central Thickening" is a misnomer. However it has been in use for so long I think everyone understands the term.
Unfortunately it gives a wrong impression of how patterns are distributed. There has been so much incorrect information based on limited, non-statistically supported data that we can ill afford to continue to have inaccurate discussion. In my opinion, there has never been truly accurate data pre Jones. Gun writers of the past get a pass from me due to lack of solid data.
No problem with accepting that all patterns/groups follow a similar type of dispersion.
So, if you look at two patterns from widely differing chokes and shot at the distances where the patterns have equal diameter, you will find the patterns are indistinguishable.
This statement is going to take a bit more explaining to an old hillbilly. I simply find it unbelievable that load with a 10.5:1 ratio would ever be identical to one having a 2:1 ratio at any at range.
Hillbilly you may be, Miller, but you are a very smart one. Chokes function is to stretch out the trumpet. Think of open choke as a coronet and full choke as one of those long ceremonial trumpets. If we look at the pattern where the trumpet diameters are the same, we will find statistically identical patterns. Think carefully. Full choke patterns at 40-45 yards perform more or less identically to IC at 25-30 yards. Same performance implies same pattern distribution.
Other factors also have an effect on the pattern, a major one being the choke.
Choke is the major influence as to how quickly the pattern blooms. Note that bloom and wither do not change the distribution. It is a Rayleigh out the muzzle and a Rayleigh when it hits the ground.
Seems obvious that some influence comes into play when dropping from the 28 to the .410.
The only appreciable difference I'd expect would come from differing pellet count. Same pellet count and same choke effect should equal the same pattern diameter nominally.
My "Personal Opinion" until proved otherwise is the major factor here is the much higher percentage of the shot which come under direct influence of the choke.
I don't think choke contact is an issue. Even though shot acts only as a semi-fluid, it seems to me that choke effect is typical fluid reaction to a constriction/nozzle in a flow field. I would contend that all the shot is under direct influence of the choke. It is clear that the shot is more or less incompressible and will accelerate (front of the shot column to the back of the column as it flows through the constriction) to maintain mass flow rate. The only energy available to support this acceleration is the shot column internal pressure. The pressure drop will reduce pellet-to-pellet spring apart and will reduce the "sideways wind" of the air entrapped within the column. Thus, the pellets subject to more choke effect will have lower "sideways" velocities and will take longer to disperse compared to less choke effect.
DDA
