Let me add my recent experience to this so that you can take care if you return the gun. You can't just pack it carefully; you've also got to take a lot of pictures. For someone to say that they "didn't see the pits" right there in the chamber is a bit ridiculous. Right? I don't know anything about your seller, but don't assume that this bit of trouble will simply end when you return the gun.
I recently picked up a Manhattan Arms 16ga off Gunbroker. If you aren't familiar, Manhattan Arms was one of the trade branded guns that were actually The Fulton by Hunter Arms. None of the Hunter Arms trade branded guns turn up very often in 16ga, so I was excited to see one.
The gun looked good n the internet, with nice colors but the pictures were a bit blurry. Listing said EXCELLENT. At $430 I purchased with assurance that the listed 26" barrels were uncut. So the EXCELLENT condition gun arrives with the light handling marks promised in the wood and metal, but also with about a dozen dime sized areas of pitting up and down the exterior of the barrels. The pits had been covered over with cold blue so that they wouldn't show in the blurry pictures. Naturally, the seller claims to have missed those imperfections. Uncut barrels show up with a small gap between the barrels and measuring 26-3/8" instead of the listed 26". Obviously shortened. The auction was AS-IS, which I hadn't worried about since the seller on Gunbroker: Freeman_Arms in Drexel Mo had promised the gun in excellent condition.
So we start going back and forth, politely even though this person starts saying the same things as your seller. We haggled back and forth about returning or a significant refund but my fairness was always met with another attempt to nickle and dime. Gun was carefully packaged and upon receipt the seller says, "Well I got the gun back but you aren't going to be happy. The forearm got loose and chattered along the barrel, getting in to the blue. I see the package was insured. You might file a claim with insurance."
Surprised? Yes, I was, but I shouldn't have been surprised at all given the earlier misrepresentation.
I asked for pictures of the new "damage", which I was fortunately able to match up with my own pictures. If I wouldn't have had the pictures then I am confident the dealer would have continued down the path of claiming the gun had been ruined by the forearm. I was incredulous that they would claim a tiny scratch to the blue was detrimental to value of a gun that had rust pits and shortened barrels, but there you go. DOCUMENT. DOCUMENT. DOCUMENT.
Naturally, this gun is now for sale again on Gunbroker, only now at a higher price but incredibly - still no mention of the rust pits, cold blue, and the barrels are still misrepresented as being 26" in length. Go figure.
