The legal risk exists regardless of the material used to manufacture the keychain or its intended use by the owner. Law enforcement agencies have conducted numerous operations to seize these items and prosecute individuals involved in their distribution and possession. Consequently, the consensus among legal experts and firearm safety advocates is that these items represent a significant legal hazard rather than a harmless novelty. Understanding the strict definitions of firearm components under federal law is essential for avoiding inadvertent violations of the NFA.
: It sits behind the trigger group and trips the sear as the bolt closes, initiating the next round's firing automatically. Drop In Auto Sear Keychain
The ATF distinguishes between "replicas" and "readily convertible." A plastic keychain that bends and breaks under finger pressure is likely legal because it cannot be used as a sear. However, a 3D printed part made of high-strength polymer (like nylon or carbon-fiber PEEK) that can survive for even one cycle of automatic fire is illegal. The technical term is "readily convertible." If a person with basic tools and a drill press can make it functional, it's a machine gun. The legal risk exists regardless of the material