Let's not forget that composite barrels on American double guns were generally finished black/white and that brownish barrels result from conversion of the black ferric +3 oxide to ferrous +2 oxide that’s commonly referred to as rust. That generally happens from long term exposure to water/humidity. Here's an original Lefever that came from a dry climate area.

Yes, and there are those with replacement parts, eh, Mike? I still think we are "originals.":rotf:

I like Mr. Gorman's answer best.

If the barrels need to be refinished, refinishing probably adds the cost of refinishing. If they don’t need to be refinished, probably zero.

Let’s not forget, a whole lot of shotguns had their Damascus barrels blacked over to look like fluid steel after fluid steel became popular. We’ve all seen them. I have a beautiful old Thomas Horsley with blacked Damascus barrels. I’ve chosen to leave them as is. However, removing the black and brining out the Damascus pattern under it certainly would make it more correct and I believe, add value. I simply wish to keep the gun as it came to me and enjoy it. To me, after learning some hard lessons, “just shoot it” is my default unless the gun is unsafe in its current condition.

I think the value is in the eye of the beholder. If you’re looking for a 100% or as close as possible condition then refinished bbls may not float your boat. If one is looking for a quality shooter or just a nice looking gun then it shouldn’t matter.

Very well stated Mike.

In the past I have witnessed an American double which had been completely refinished except for the damascus barrels. The barrels retained about 85 -90% original finish and were left as is. The appearance of the assembled gun was a huge disappointment.