My problem is resolved.  Knowing it was the chamber and not the extractor, I pulled the barrel again and focused on that.  

Here's the history on this chamber:  I had a custom .38-55 reamer made to my dimensions after I ordered the Starline brass and prepped sample ammunition.  I had a well known gunsmith that I have no complaints about and highly respect his work fit the barrel.  He told me that the brass was slightly tight and hard to chamber, the reamer should have been .001 to .002" larger at the breech.  I told him to go ahead and polish it out and we'd work with it.

We used it with new brass, and it worked okay.  It only really gets used once a year by my wife at Quigley.  Next year, some of the fireformed brass was hard to insert; we sorted it and fired the hard to chamber stuff in practice, the good stuff in the match, and it was okay, but hard to eject.  I polished the chamber a bit more and put it away for another year.  It got used once or twice more, and it always had problems both loading and ejecting the brass.  I was too busy to troubleshoot it, so we lived with it.  I seated bullets deeper and it was easier to chamber the loads.  Then, it wasn't used for I think 6 or 7 years.  In the mean time it was stolen, recovered buried under the floor of a shed (with associated rust and damage) and I refinished and rebuilt it.  Last year we went to Quigley again.  It hadn't even been test fired, I assembled the rifle and we loaded the bullets the day we left and just went.  Time was short; we both worked and lacked spare time.  My wife had a lot of trouble both chambering and ejecting the loads.  So, now being perennially unemployed, I decided to fix it the week before we go to Quigley this year.   I haven't loaded the ammo yet, but I have cast the bullets. 

With the barrel out, I checked and no evidence of a ring in it.  I used 400 paper wrapped on a dowel, and longitudinally polished the chamber.  After doing that, I can see an untouched spot about 1/8" wide about 1/3 of the way around the chamber, just in front of the web area of the case.  Obviously an artifact of either the original smith or I radially polishing the tight chamber.  So, I started with 320 and radially polished behind the area until I was cutting evenly through that spot.  Then, I again longitudinally polished with 400, and no spot appeared.  So, I polished the entire chamber with 600, and test fired. 

It works with ammo that stuck before.  We'll test at Quigley next week!

Test at a match?  Not the best idea.  Coming from someone who will be testing my 25 Hornet again at Tommy Mason's match.