Gr8day,
Sounds a lot like a 16 bore Martin BLE that is one of my favorite quail guns. It sold for around $1.4K several years ago. Not much case color left on the receiver and some simple border engraving. Mine weighs in at 6 lb 2 oz with 15 1/2" of pull to a checkered wood butt. Very dynamic gun too. Had to work on an ejector once, but it was standard Birmingham boxlock stuff with Southgates.