Well understand one important thing here as well. Chester took a lot of guns, particularly from up around here and "tweeked" them. Some guns were initially done by someone else and sent to him. Occaisionally he would re chamber them, more often he would relap them if possible to get a more progressive taper. He fit very few Hart barrels, for instance, because they were, at that time being made on the large side of what he could use and ran, often, to .2180" across the lands.
He got to a point where he wanted something that ran .2170" but would go up to .2175". He only measured with pins not by slugging, as he believed that yielded better sealing in the bore.
If I knew a bit more about the provenance of some I could venture an educated guess.
The "Lugnuts" example, for instance, was likely first fitted by Tommy Fargnoli and relaped by Chet on a Hart barrel in particular.
Loughnot and I got to where we sourced some barrels from Tim North with Chesters ideal dimensions in the Broughton 5C configuration. They were to be for a couple projects Chet was going to do but that's when he passed and those never got completed. A lot of the 5C barrels Broughton made did very well as fit by Gordon and many of them were right in that .2168" .2170" sweet spot.