Well.... not a satisfying update I am afraid. But a little interesting I suppose.
Short story is that I have not shot it again since I got it back from the smith a couple weeks ago. As I noted earlier, the trigger became "floppy" after the last time I shot it. I took it in expecting it to be a spring issue. The smith completely disassembled and cleaned it out (said it was very dirty inside - likely it had been 100 years since it was last cleaned this well...)
He diagnosed the floppy trigger as a worn sear. He searched all his sources and contacts and was unable to find a replacement sear. He is able to manufacture parts so he tried 2x to make one. He was unable to replicate the spring tension so the trigger was impossible to pull. He outsourced it to another fabrication place he uses from time to time and they had a similar issue - although the trigger would pull now, it had a 25 pound pull pressure!
He did fire it with some factory brass and said he thought the dimpling was a bit lighter than before. I looked at the brass and the dimples did look a tiny bit shallower - perhaps 10% shallower than the original dimples. I am not sure I would call it a step-change from prior but it was marginally better.
I will say, I really like this smith. He spent HOURS diagnosing, cleaning, researching, fabbing parts and testing. Because he could not fix the issue, he did not charge me a dime. I immediately dropped off two other rifles that I wanted some work done on. Contact info for anyone interested:
Pollock Precision Gunsmithing
Evan Pollock
pollockprecisiongunsmithing.com (208) 889-8380
Sagle Idaho
So unless I can find someone who can look it over and fix/replace the sear, this firearm will sit in the safe. And still no solid theory's on why it dimples.