GP100man said:
Did S&W ever make a revolver with a full lugged barrel & a recessed cyl. ??? [...]
Taken literally that's an easy question with an answer that does not help. All S&W .22 rimfire revolvers have been recessed since approximately the mid 1920s and most K-22s have been full lugged since 1989. More to the point no L frames [686/586] were pinned or recessed and no pinned and recessed model 19s were full lug. If you change the question to "were any
pinned and recessed S&W center fire revolvers full lugged I'm pretty sure the answer is no or only a few odd balls.
As long as you are looking at S&Ws with traditionally installed one piece barrels all K frames have metal removed from the bottom of the barrel under the forcing cone providing clearance for the yoke. L frames were primarily engineered to get rid of the stress riser that flat created. If you don't handle K and L frames enough to immediately recognize one by size looking for the flat spot seems easy.
Incidentally, L frame barrel threads are larger diameter than K frame threads. Rethreading would not be quick or inexpensive but I'm acquainted with the proud owner of a 19 wearing a 4" 586 barrel. Similar rebarreling was once done for PPC with Python barrels. However it's possible the 19 you looked at didn't get a 586 barrel to create its owner's dream gun. S&W no longer sells replacement 19 barrels so a 586 barrel may have been the best option after the original barrel's flat spot cracked.