Approved alternate method or procedure for licensed manufacturers and importers of firearms, and makers of 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.  Supersedes ATF Ruling 75-28, and clarifies ATF Industry Circular 77-20.

Any person (including any corporation or other legal entity) engaged in the business of performing machining, molding, casting, forging, printing (additive manufacturing) or other manufacturing process to create a firearm frame or receiver, or to make a frame or receiver suitable for use as part of a "weapon … which will or is designed to or may readily be converted to expel a projectile by the action of an explosive," i.e., a "firearm," must be licensed as a manufacturer under the GCA; identify (mark) any such firearm; and maintain required manufacturer’s records. A business (including an association or society) may not avoid the manufacturing license, marking, and recordkeeping requirements of the GCA by allowing persons to perform manufacturing processes on firearms (including frames or receivers) using machinery or equipment under its dominion and control where that business controls access to, and use of, such machinery or equipment. ATF Ruling 2010-10 is clarified.

An office or repair shop used in connection with the manufacture, etc., of explosive materials are not "inhabited buildings."

Alternate magazine construction standards for storage of electric blasting caps with other explosive materials are prescribed.

Explosives manufacturer license required for certain companies that manufacture explosive materials for use in their own operations.