This is probably the back porch of the building in the previous image, with Annie teaching ladies to shoot. They look (from left) to have a revolver, a lever action, and 2 possibly Remington Model 12 .22s which Annie was known to use. Annie is 2nd from right



As said, there have been lots of sighting devices for the muzzle.

1894 Parker D Live Bird Gun courtesy of Gordon Lew



Wilbur Gun Sight is the only one I've found for the breech
October 1919 Forest & Stream
https://books.google.com/books?id=F99JAAAAYAAJ&pg=PA568



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