From the Summary: "The Department of Justice is amending the regulations of the Bureau of Alcohol, Tobacco, Firearms, and Explosives ('ATF') to codify into regulation certain provisions of the Omnibus Consolidated and Emergency Supplemental Appropriations Act, 1999. This rule amends ATF's regulations to account for the existing statutory requirement that applicants for Federal firearms dealer licenses certify that secure gun storage or safety devices will be available at any place where firearms are sold under the license to nonlicensed individuals. [...] The regulation also requires applicants for manufacturer or importer licenses to complete the certification if the licensee will have premises where firearms are sold to nonlicensees. Moreover, the regulation requires that the secure gun storage or safety devices be compatible with the firearms offered for sale by the licensee. Finally, it conforms the regulatory definitions of certain terms to the statutory language, including the definition of 'antique firearm,' which is amended to include certain modern muzzle loading firearms."
Federal Register: http://www.federalregister.gov/
Federal Register (January 4, 2022), v.87, no.2, p.182-194