The store admitted they misled me, apologized and took the barrel back, paid for shipping and refunded both. I asked for a deal on the barrel I got (cost +5% or something reasonable), but that was a no-go. I'm not satisfied and think they could have done more, but I'm not hugely mad about it either. In the interim I missed out on a used barrel at a good price.
Just a big waste of time. Meh.