That's great information thank guys.
Perhaps I will rethink the Nitre blue,it looks nice but I understand it does not hold up well.
If most UK gunsmiths are now using hot caustic bluing salts for furniture on old guns then I guess that's accepted practice.
When we say top lever,bottom plate etc I assume the associated screws with these are also blacked?
I will drop Barrel browner a line,thanks.