: Vendors may claim the item is a "novelty" or "pre-81" device that is legal to own as a collectible. This is legally false ; under current ATF interpretations, any newly manufactured device capable of this conversion is a prohibited machine gun. Legal Status and Federal Penalties What Can the ATF Do About Converted Machine Guns?
Another myth: "It’s legal if you never install it." Also false. Possession of the intent-to-convert device is the crime. You don’t need an AR-15 in the same room. You don’t need to have attempted installation. Simply having the keychain on your person is constructive possession of an unregistered machine gun. Drop In Auto Sear Keychain