Argo44, thanks for the information and the chart, which I'd previously seen but had not fully appreciated the start date of.
I suspect the images you can see are of the Mantons I was comparing the Cutler somewhat unfavourably to.
Here are some more images of my gun. Hopefully these will display properly (I have yet to figure out why some of my Dropbox links work when others don't):

[img]https://www.dropbox.com/scl/fi/ypa2...rlkey=3147ubxnhe3ixer6lyx2dtart&dl=0[/img]

[img]https://www.dropbox.com/scl/fi/b9sb...rlkey=tggy5qkqmlivxl9pxazcr4g1u&dl=0[/img]

[img]https://www.dropbox.com/scl/fi/7ns5...rlkey=2thc2dkqpd5sl0xyt69nulht8&dl=0[/img]