Welcome, Profitt- as said, stop by the intro thread and say howdy- and welcome to the forum.
In the meantime, gunpartscorp.com has 20 g barrels for the Mossberg 85B, which should fit- but to tell you the truth, they are pricey- about half the cost of the entire shotgun- AND- if you are not a gunsmith, and do not have the specialized tools to replace a barrel, I would urge you NOT to try this yourself. Have a smith do the replacement.
There ARE two used barrels over on gunbroker.com for $25.00 each plus shipping- or an entire complete Mossberg 85D for $99 plus shipping (and ffl fee from dealer you get it shipped to)
What we have here is... failure- to communicate.