That's a broad and inaccurate statement. Destination, configuration, options can and quite often do add value and in some cases, quite significantly.
Probably, in this case, it will add little unless the shipping info offers something interesting regarding a LE pipeline.
I stand by what I said.
In most cases, the presence of a factory letter will not increase the value of a S&W revolver, unless it is in an unusual configuration.
I have seen the factory letter for the S&W revolver that Teddy Roosevelt bought just before he left to fight the Spanish American War. As I recall it was a nicely engraved 44 Double Action, chambered for the 38 service cartridge. It sold at auction for a lot of money, sorry I don't remember how much. But in that case its provenance was already known. The revolver was valuable because it was owned by Teddy Roosevelt. The letter was just icing on the cake.
I have about a dozen S&W factory letters. Some of them came along with the revolver when I bought it used. Other revolvers I had lettered myself.
In none of these cases did the presence of a factory letter increase the value of the revolver.
One might ask then, why bother to letter a S&W revolver at all?
I can tell you that in a couple of cases I was intrigued and wanted to know the history of a certain revolver. I have an old, K-22, which I got dirt cheap because the finish was in pretty poor shape.
When I mentioned it to Roy Jinks, the official S&W historian, he said this revolver had an interesting history and I should letter it.
So I did. It turned out the revolver was shipped to the Providence Rhode Island Board of Public Safety in 1932. The letter goes on to state that this one was part of a shipment of 6, and it appears that the Providence police department bought them for their pistol team. They were billed at $22.19 each.
So the letter did not add any value to this old revolver, it just gave me some interesting history on it. I will add that I have several old K-22s, but this worn old one with its incorrect grips is the most accurate of the bunch.
A few years ago I ran across this nice New Model Number Three at a local gun show. I got it for a good price. When I started snooping on the S&W forum some members told me they thought it was part of a shipment to Japan.
I lettered it and the letter stated that it was part of a large shipment of revolvers shipped to Takata & Co., Yokohama, Japan in 1896.
It is interesting to speculate how it got back in this country, perhaps in the duffel bag of a GI returning from WWII. But that is just idle speculation.
If I ever sell it, I will include the letter. Other than offering some interesting information about the revolver, the letter will not increase its value.
However, if the letter showed the revolver had been shipped to the emperor of Japan, that would be a different, and very rare story.