The Bangor Punta marked box is period correct for a no-dash 686, but no end label is certainly suspect and one easy answer might be that it formerly had a non-matching end label and the previous owner peeled the label rather than having a non-matched box.
It is also possible that S&W had the revolver back in their hands for service (or warranty work) and shipped it back in a new box they had in stock that never had an end label.
At this point, with the evidence you have on hand, there’s never going to be a way to prove that this box is the original.
But it is certainly period correct and appears to be in fantastic shape for it’s age.
Bangor Punta sold S&W by 1987. S&W has a reputation for using everything in stock until supply is exhausted, so even that date doesn’t tell us too much. A typical company would have tossed out boxes displaying the former owner’s name, but I don’t know if S&W did.
Two more questions…
1) On the left end of the box, does it look like a label HAD been there and later removed?
2) And on the frame flat behind the yoke, is there an “M” stamp under the model number?
If the answer to #1 is yes then it seems the only logical answer is that no, this box is not original. If the answer to #2 is yes, then this revolver made a return trip to S&W, which *could* support the idea that it got shipped back in a new box.
