Hello Sir!
I'd definitely like to see more detail of this set of barrels.
They're looking pretty crude and haggard in these photos, but there's likely to be more of a tale for them to tell.
The interesting style of sleeving has a bit of MacNaughton or C&H to it with that 'chamber' detail...
I've been looking at a micro-mini toplever back action hammer double I have that I've 'been meaning to convert' to 25-25 Stevens for the past couple (three?) years. I'd wanted to do something similar with the sleeve job on that one, but I don't think I'll be going this route with the 'long-shoe' method seen above.
There seems to be a very thick wall (or thick filler rod fillet) at the sleeve joint where the barrels emerge from the 'chamber block'.
I think I'd prefer a joint much more like the MacNaughton I show here.
My little project needs forend wood anyway!
Cheers
Tinker