Hi all, I have 2 Dickinson's a 16ga and 28ga.  The 16ga has a ST, I use it for winter hunting with gloves.  The trigger pull on this one is heavy, but usable for hunting. The 28ga has DT and the pulls are very nice, pretty light, very crisp and no creep.
What I found interesting in Bruce's article is the constriction of his choke tubes.  His were much more open than what the tubes are marked.  My 16ga tubes are on the money.  My 28ga tubes are more open than marked.  The Cyl is Cyl (.000), The IC is Skt (.002), the Mod is Lt Mod (.009), the IM is Mod (.012) and the Full is IM (.018)
According to other Dickinson owners, looks like the tubes do vary and look to be all over the map.  I wonder if the bore diameters are consistent or vary that much.  I can't see the tubes varying that much, but who knows.  BTW the bore diameter on my 28 is .550  right and .551 left.  Pretty much dead on.
Best,
Greg