Not sure if this is a little OT,but it is a rifled single shot and of large bore.

I would like to put a full length brass tube sight on an original 1868 Remington rolling block.
I gather these were used back in the day and would like to have one constructed to conform as close as possible to an original.
I have never seen one in person and can find nothing on the net as to how they were constructed.
I imagine there is simply a screw in aperture at the breech and perhaps a blade at the front,although I have been told some had an etched glass element at the muzzle.
The more complicated part I suspect would be the bases ,as they would have to incorporate windage and elevation.

If anyone has an original or knows how they were constructed I would appreciate it.

Cheers,

GDU