The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) authorizes licensed manufacturers and licensed importers of firearms, and makers of National Firearms Act (NFA) firearms, to adopt the serial number, caliber/gauge, and/or model already identified on a firearm without seeking a marking variance, provided all of the conditions in this ruling are met. Licensed manufacturers seeking to adopt all of the required markings, including the original manufacturer’s name and place of origin, must receive an approved variance from ATF. ATF Ruling 75-28 is superseded, and ATF Industry Circular 77-20 is clarified.