I have not previously heard of this kind of internal Barrel configuration.
You could apply to Colt for a 'Letter', which most likely would say, if this were a special Order Revolver, which had been made that way by Colt.
Far more likely though ( in my imagination ) is that the unusual interior Barrel condition was done by someone not-Colt, to modify an existing Revolver to their purpose.
Have you tried it with Bird Shot Shells to see how it Patterns at various distances?
Post some images of the Revolver!
You could apply to Colt for a 'Letter', which most likely would say, if this were a special Order Revolver, which had been made that way by Colt.
Far more likely though ( in my imagination ) is that the unusual interior Barrel condition was done by someone not-Colt, to modify an existing Revolver to their purpose.
Have you tried it with Bird Shot Shells to see how it Patterns at various distances?
Post some images of the Revolver!
