Originally Posted by John_Deer
I doubt you will find a rifled slug barrel for your Mossberg with an extended magazine. In the end you will want another gun for your slug barrel. Once you see how accurate a good sabot is you will want to mount a scope on your slug gun. A new slug barrel is over $100. You are well into a field model 500 that is drilled and tapped for a scope with $100. Plus it will have a nice wood stock that feels warm on those icy mornings.
I agree ^^^. I picked up used Mossberg 835 that was like new for $200 and a somewhat beat up clone of a Mossberg 500 for $75 that needed a good cleaning and now functions perfect. Look at your local gun stores and try to find a used barrel, as long as the inside looks good a little Duracote can go a long way.