The one above was, The Donar gun was an EMF Heritage 61 London model.
I'd have to look up the date code; I'm thinking early 2000's
(edit [CC] 2008)The new 51 barrel was of unknown vintage, no DC was on it.
The rather stupid part is ... I'm guessing I have north of dumb money invested.
The guns initial purchase, the Kirst Cylinder purchase, acquiring the 51 barrel & have it lined.
Considering, all Pietta, BP Only, and Made in Italy stampings were shaved, both barrels and Kirst were then all nitrate hot bath blued.
But I have a convertible conversion, rather unique, dare I say one of a kind.
as an aside, I have swapped Uberti OT & BP barrels as well with no issue.
as you implied not cross kit bashed between the two manufactures though.