A couple of thoughts:
Do we know what the dolls head gap looked like before the hook was reset? Isn't it likely the dolls head experienced wear on the front edges and the gap existed prior to the hook work?

The OP’s fourth picture is about as perfect as it was when it left “that dusty little plant down in Meriden” but I have seen one or two perfecter examples. I have the pics at home on my laptop.
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I am thinking Keavin may be onto something. When the gun was loose as it was closed what should not have been a wearing surface became one. With things loose the front edge of the dogs head would wear against the hardened frame as the gun is closed. This could create wear that becomes evident when the gun is tightened up. Could this be part of the purpose of the dolls head, to keep barrels tight to the breech face? All in all perhaps yet another reason not to leave a gun that is loose that way so unnecessary wear doesn’t occur at the dolls head.

Having just said I couldn't think of a reason to mess with the breech face, you reminded me of something I had seen on a gun another member had and sent to Bachelder
The gun had been shot a lot, after it was obviously loose, and was probably shot with one barrel (right?) more than the other. Being loose to start with I suspect what Brad was describing was a hammering of the barrel face against the breech. Essentially, I'm guessing it got out of square. I can see where one smith might square it back up by machining. That would probably be way less trouble on a gun without a rib extension. In the gun that Brad repaired, I believe he built it back up with weld, then machined it square. I just remembered that the frame was cracked also, so it was probably one of the earlier lifters.