Armbar:

The bottom line answer to the question that I think you're really asking is - no I don't know of any way to determine WHY a set of barrels was struck-off and re-blacked. Worn finish, or something else? If the work was done well, there's no way to tell.

To answer the question you asked - if the barrels of a fine double have ever been re-blacked (and keep in mind that many of these pre-war guns have been re-blacked several times), and if the work was performed correctly, then they've been struck-off, as that is the way it is done.

To refinish the barrels of a fine double, they are very lightly struck to remove the old finish, being careful to preserve the beauty of the original barrel filers work. Some hacks do this with a polishing wheel, which is never acceptable. They are then polished by hand to the desired luster, and rust blued. Again, carding is done by hand, not with a wire carding wheel.

I understand what you're getting at, but I'm afraid there's no way to know.
---------------------------------------------------------------------------