The term “firearm” is defined in 27 CFR 478.11 to includes a weapon parts kit that is designed to or may readily be completed, assembled, restored, or otherwise converted to expel a projectile by the action of an explosive, and would not include a weapon parts kit, in which the frame or receiver of such weapon is destroyed.  

Licensees may voluntarily request a determination whether a weapons parts kit is a regulated firearm by contacting ATF’s Firearms and Ammunition Technology Division (FATD).  

A weapon parts kits that is determined to be a firearm shall be recorded as a “firearm” in the licensees’ A&D records and on ATF Form 4473.