I have an 32 inch unsingle ported barrel with screw in choke that came off my Beretta 680 Trap gun that was an extra as a backup. Just don't need it anymore. I have no idea who ported the barrel, it was that way when I bought the gun. These will usually fit some other 680 series guns, you'll have to research that on your own. The bluing is well worn and pitted, so it doesn't look all that pretty. The barrel shoots just fine, but can definitely use a new skin. See pics. No center bead either, I took it off for my other barrel when I needed a new one. The barrel comes with one Briley full choke tube. Price indicates the need for new bluing but if you want an unsingle barrel for your 680 here's a good deal. $600 plus shipping.
I honestly have no idea. I got the gun around 2010 with 3 barrels, a different unsingle, an over under plus this was thrown in as a spare barrel. I never asked what caused the pitting since it was only a back up. The other 2 barrels were in great condition. Last year I sold the gun as an unsingle with the other unsingle barrel. I sold the over under and finally got around to selling this barrel. It should shoot just fine, but it is an ugly duckling. A new bluing and it should be right as rain. I actually just answered a PM from another member interested in buying it.