I doubt there have been any Remington Rolling Blocks made in about a hundred years. It is possible that yous is a reproduction or more likely someone put a new barrel on it.
It would have probably required some action work in addition to being chambered for the little carbine round. The rolling block was chambered for the fairly high pressure 7mm mauser which is rimless so it clearly could have been done.
I doubt there have been any Remington Rolling Blocks made in about a hundred years. It is possible that yous is a reproduction or more likely someone put a new barrel on it.
Pedersoli makes reproductions.
https://www.youtube.com/watch?v=9vEAwIIUXvs