As a point of interest and follow up to this thread. I have found a US barrel maker who will make pretty much anything up to and including a 4 bore. Oregon Barrel Works. I have not personally used their barrels yet but I find nothing but good reviews. I will be ordering a pair of 14 or 12 bore barrels from the later this year.

http://www.thegunworks.com/custprodgun.c...at1Name=Barrels

PS: "The Gun Works" are the same people as OBW. They just don't have a separate site yet.