The available inventory on Mossberg's website is notoriously unreliable and inaccurate. It apparently doesn't get updated very often. The wait time for an e-mail response from their "contact us" feature averages somewhere between two weeks and forever. However, with a five minute conversation you could have your new barrel on the way. The CS reps have access to actual on-hand inventory and can place your order on the phone. They typically say there's a 6-8 week wait for delivery, but most orders ship well before that. We have had multiple members order barrels in the past couple weeks that showed out of stock on their website, were told a 6-8 week wait, and received their order in right at one week.
Either way, good luck finding your barrel and we look forward to a range report once you get it set up...