Really need more pics to evaluate that gun; but on a custom order gun like this 4E, the customer could certainly specify, and Hunter Arms would provide, his preference for a flat or concave rib. If there are concerns that the barrels may have been replaced, I suggest you post additional pics of the barrel flats and water table; as well as the underside of the fore iron and fore iron hanger lug. I also suggest you post more detailed pics of this gun; for if the balance of the gun is in as high original condition as it appears the gun may be from the two photos above, it is an even rarer gun. I can only recall having seen two other 4E 20-bores in my lifetime; one of which had been used a lot and to my thinking would be classed as a shooter grade (the old codger with the gun had it way over-priced at $20K!). As to its value I have no idea; but again, the gun is very rare and even more so if it truly is in as high an original condition as the photos make it appear to be; and if it is, it would fetch a premium from a Smith collector.
