I hope someone can assist you since I can't help but put myself in your shoes (almost) since I wanted that gun for my wife simply because it had the 32" barrel. She has one just like the one you got, with 30" O/U barrels, and I thought the 32" barrels might smooth out her swing to the second target.
It looks like he spent the money since his posts show that, right after he sold you the gun, he sent a PM on a Browning and the seller fairly quickly posted a "Sold" on the thread.
On most of these disputes, the seller eventually responds with his side of the story and TS.com then becomes split on who was at fault, what the buyer or the seller did wrong, and how the transaction really should have been handled.
In this one, I eagerly await his explanation of how the missing two inches came about. But, I am probably waiting in vain.
He is correct that you probably can get most of your money back by reselling the gun. But you should not have to do that and a person with some integrity would probably acknowledge the mistake and at the least offer the difference between the value of 682 34" barrels and 32" barrels.
Hopefully, he will do that though the real right thing to do is to take the gun back and refund your money.
Bob