Firearms and Ammunition Technology

Image of a gun with a laptopThe Firearms and Ammunition Technology Division (FATD) provides expert technical support to ATF, other Federal agencies, State and local law enforcement, the firearms industry, Congress, and the general public. This Division is responsible for technical determinations concerning types of firearms approved for importation into the United States and for rendering opinions regarding the classification of suspected illegal firearms and newly designed firearms. Further, FATD provides the U.S. Department of Justice, State prosecutors' offices, district attorneys' offices, and military courts with expert firearms testimony on the identification and origin of firearms and other matters relating to firearms and the firearms industry. The Division maintains an extensive firearms reference collection, as well as technical firearms reference files and library and firearms databases.


The mission of the Firearms and Ammunition Technology Division is to serve as ATF's technical authority relating to firearms and their classification under Federal laws; to respond to law enforcement agencies requests to test, evaluate, and provide expert testimony on firearms and ammunition; and to provide technical services to the firearms industry and other members of the public.

FATD support to the firearms industry and the general public includes the following areas:

  • Responses to technical inquiries.
  • Testing and classification of products submitted.
  • Curios or Relics (C&R) determinations (see the C&R page prior to submitting a C&R inquiry).
  • Import evaluations.
  • Providing marking variances to the firearms industry

Marking Variances

Guide to Marking Variances

ATF F 3311.4 Application for Alternate Means of Identification of Firearms (Marking Variances)

Applications for alternate means of identification of firearm(s) (marking variance), ATF Form 3311.4 and letter applications should be submitted electronically at or by fax at 304-616-4301. Applications also may be mailed to:

Contact Information

Firearms and Ammunition Technology Division 
Email: Voice: 304-616-4300 Fax number: 304-616-4301

Last Reviewed October 5, 2020