I picked up an Cimarron/Uberti 1885 Highwall in 38-55 recently. I haven't had a chance to shoot it yet. I ordered some Starline brass. I will try fireforming out some 30-30 brass later in the week. I tapped out the buckhorn rear sight and screwed on a Marbles tang sight.
I did an impact chamber slug today. The chamber is ~2.130" long to the beginning of the throat. Bore is .374". Grooves are .382".
No questions yet. Just sharing the chamber dimension information in the event someone else was considering one of these.
-ktw