I forgot to comment on the outer sleeve. I have heard about these, but yours is the first I have seen. Most of these guns are sent to distributors, gun shops, hardware stores, etc., and would have been discarded before putting the gun on the shelf or in the case. I wonder if that revolver was shipped directly to your great-grandfather?
As for the serial number, I have seen examples of where a similar serial number stamped stock was put on the wrong gun. Honest mistake and still accepted as "matching". I can only guess, but my thought is that the boxes are a different story. This assembly should go something like this. Guns come to stations for packaging. Worker picks the correct end tag and box to match the gun. After everything is put in the box, including the gun, the worker turns the box over and places the serial number on the bottom. To transpose one number in your mind while writing would not be unusual, but that number is quite different. Still, the gun appears to fit the box very nicely without issue. Remember that the box was never constructed to last, but rather get the gun to the owner without damage. The corners of these boxes are only held together by two pieces of paper glued to the inside and outside of the pasteboard, so are inherently weak. With the sleeve and company address, I would letter it to see what you find out about the recipient and the front sight.