What are you trying to find out? I have never found anywhere to determine year of manufacture of SKB doubles like 100s, 200s, 280s, etc. I also have never found any correlation between serial numbers and the exact model of the gun. There are a lot of variables on SKBs. Most 100s have a splinter forearm but not 100% for example. SKB Shotguns USA imported shotguns from the Japanese factory during the period 1988 to 2009. These shotguns will have our importer’s mark (G.U. Omaha, Ne.) on the left side of the barrel under the forend. In most cases, the shotguns will have a serial number prefixes of either NS, NSG, NA, and AS. SKB Shotguns USA does not have access to records from previous importers. Shotguns imported by 'Ithaca Gun Company' were manufactured from 1966 to 1977. The catalog links presented here are for informational purposes only. Review old catalogs from ITHACA below. SKB Shotguns USA does not have access to records from previous importers. Shotguns imported by 'Ithaca Gun Company' were manufactured from 1966 to 1977. The catalog links presented here are for informational purposes only. Review old catalogs from ITHACA below.