Honestly, I think I need to provide pictures. Perhaps I'm not using the right terms to describe what I'm seeing but pictures will have to wait until Monday when I am back.
But if you imagine the cylinder slot, the edge where the bolt strikes, has been made concave to a degree by the repeated impacts, (as far as I can tell...). And, to my eye, that edge of the cylinder slot has bulged as a result to a small degree: the material being displaced had to go somewhere...
But the long and the short of it is that one prong that cams on the hammer is either too short (if I want the bolt to drop virtually straight into the cylinder slot) or too long (if I want to have it drop halfway between any two given cylinder stops so that it is sure to engage the cylinder as it turns.
The latter option is fine by me as long as it is fine by the gun: it is certainly easier to shorten a metal part than it is to lengthen it.
I incidentally found another thread on here that seems to show similar cylinder marks although I have to read it more carefully. I'll
link it here as the images show similar effects as on my Uberti: posts #29-31 in particular (second page)