I have the "parkerized" finish on my 835, and have fired around 2000 rounds through it with no sign of any finish damage. The Mossbergs come with a 10 year warranty, perhaps you should contact Mossberg. They may get you to send that barrel back to them, and refinish it, or send you a new barrel. You are using it with the choke tube screwed in aren't you? Just a thought...
I have to admit the 3.5" shells with a heavy waterfowl load kick like the :evil: devil. You have to really be in a situation like pass shooting geese, before you need that kind of punishment.
Whitecloud. Adjustable sights?? I'd like to learn more about those. Dose he have beads that screw up and down or what?? I could turn my Mossy into a trap gun if I could do that! Trap guns usually pattern on the high side. Say 70% top, 30% bottom. This allows you to shoot a rising target, without having to cover the target, with the barrel, like most field guns.