W&C Scott. GE Lewis, G&S Holloway, Greener, Tolley, Midland, BSA, Vickers, Dickson, etc have all produced fowling guns, as have most all Brit makers. 3" chambers aren't common, but they are out there. Your best bet will be a heavy proofed, 2.75" chambered gun built for water fowling or finding a Brit short chambered wild fowler 10 bore. Boxlock guns will be easier to find than a sidelock, and personally I'd prefer the BL if it was my water fowler. If 5k is your starting point, you have a plethora of choices out there. Lots of inventory stuck in limbo at the moment and Brit waterfowlers are notoriously hard to sell for dealers/individuals.