Nice Model-1868 and fine shooting and load information 'Parashooter'.
Interesting thread! ..... hey, where's that Hosmer "kid"?
Sorry I missed this one. Really have nothing to add to the excellent previous posts, except to say that I believe the only purpose of the little beveled pop-up pin behind the chamber was to hold the fresh cartridge forward (against the pressure of the horse-shoe spring) so that the block could be closed when loading. I do not believe it plays any positive role in the extraction/ejection sequence - if anything it would be a hindrance at that point.