The letter specifically targets the following regulations:“Engaged in the Business” Rule : This rule clarifies when individuals are considered firearms dealers, thereby requiring them to conduct background checks. atf.gov: This rule clarifies when individuals are considered firearms dealers, thereby requiring them to conduct background checks. : This regulation reclassifies pistols equipped with stabilizing braces as short-barreled rifles, subjecting them to stricter controls under the National Firearms Act. “Ghost Gun” Rule : Aimed at regulating unserialized, privately made firearms, this rule requires background checks and serial numbers for gun kits. : Aimed at regulating unserialized, privately made firearms, this rule requires background checks and serial numbers for gun kits.