FYI as a follow-up on another thread.
Awhile back there was a post & discussion about a factory non-safety live bird gun. In this post there were some pictures of the underside of the top tang that had a couple of V-Notch cuts going across the tang. The question arose if these cuts were factory or not and what the use would be for them.
Recently I took a couple of pictures of a Repro. single trigger gun and it has these same notches cut in the top tang. In the pictures you can see these notches are used for the safety slide spring on a single trigger safety. Double trigger guns use a different safety notch arrangement.
Another place to see the V-notches on a single trigger gun is in the Parker story volume one page 142.
All the best,
Paul