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Bureau of Alcohol, Tobacco, Firearms and Explosives

Washington, DC 20226

August 22, 2001

Open Letter to All Federally Licensed Importers and Manufacturers

The purpose of this letter is to apprise Federally licensed importers and manufacturers of amendments made to regulations that prescribe marking requirements for firearms. Specifically, we are requiring that firearm serial numbers have a minimum height of one-sixteenth of an inch and a minimum depth of three one-thousandths (.003) of an inch. Other required markings must meet minimum depth requirements of three one-thousandths of an inch.

These amendments modified 27 CFR § 178.92 as it relates to both firearms in general and semiautomatic assault weapons. In addition, the new marking requirements also apply to National Firearms Act (NFA) firearms and amend 27 CFR § 179.102 to require the same standard for serial numbers and other mandatory markings for NFA weapons.

This rule, published in The Federal Register (Vol. 66, No. 150) on Friday, August 3, 2001, is effective January 30, 2002. Federally licensed importers and manufacturers will be required to comply with these new marking requirements on all firearms manufactured and imported on or after January 30, 2002.

In certain unavoidable circumstances owing mainly to unusual firearm designs or other factors that would limit the manufacturer’s or importer’s ability to comply with these new marking requirements, alternate means of identification may be authorized as described in 27 CFR § 178.92(a)(4).

These minimum standards are necessary both to ensure that firearms are properly identified in accordance with the law and to facilitate ATF’s ability to trace firearms used in crime. The complete text of the final rule (T.D. ATF-461) can be viewed at ATF’s Web site,

Should you have any questions concerning this letter, please contact the Firearms Enforcement Branch at (202) 927-7770.

Sincerely yours,

Signature of John P. Malone

John P. Malone
Assistant Director
Firearms, Explosives and Arson