I'm going to try to explain what I saw again.There is an early model 66 no dash that I found for sale. The pictures show what I believe is the end of the hammer "pivot pin". The end of the pin is halfway covered by the cylinder release. Seems odd.
The only Smith that I have with the pin exposed is a 1917 comm. model.

Any ideas?

Strange, I have one from 1974 that does not have that pin. I have no clue. Big Larry

My 66 has the exposed pin - I had to go look!

Reread my post. I was no very clear at first.

From your description it sounds as if you are seeing the hammer stud. The studs are usually buffed flush with the outside of the frame and are rather difficult to see. If the stud on your gun is proud of the surface, I would imagine that it has been replaced by someone other than S&W.