ATF
The Bureau of Alcohol, Tobacco, Firearms and Explosives — the US federal agency regulating firearms.
Also: BATFE
The ATF (officially BATFE) administers federal firearms law: licensing manufacturers and dealers (FFLs), regulating NFA items, investigating violations of the Gun Control Act and National Firearms Act. ATF rulings — interpretations of statute — periodically reshape what’s legal to own, build, or sell, often controversially.