Thanks for the questions guys! The head of the "action pins" is the "stop" as far as insertion. Since the threaded section of the pin is next to the head, it doesn't matter because the small end is a "pin" anyway. The hammer screw on the next one ( another one of mine) may have the frame threads removed to explore a better "keeper" for that pin. The section that supports the hammer is fitted to a closer tolerance to give a more accurate travel. Hope that sheds more light on the subject.
Mike