The legality of auto sears and similar devices varies significantly by country and even within regions of a country. In the United States, for example, the laws regarding these devices can differ from state to state, and federal laws also play a significant role in regulating such items. The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) often oversees the regulation of these devices.
: A drop-in auto sear is a small component designed for an AR-15 that allows it to fire automatically without machining the receiver. Drop In Auto Sear Keychain
Sold as "novelty bottle openers" or "wall art." The legality of auto sears and similar devices
Do not buy it. Do not print it. Do not put it on your keys. If you see one for sale, assume it’s either a scam or a sting operation. If you already own one, contact an attorney immediately about lawful disposal (usually turning it over to local ATF field office). The best souvenir from the world of NFA items is a clean criminal record. Leave the Drop In Auto Sear for history books and registered dealers—not your pocket. : A drop-in auto sear is a small
A DIAS is a small component that can be placed inside an AR-15 lower receiver to enable automatic fire without requiring the permanent modifications (like a "third hole") typical of M16-style receivers.
The occupies a strange place in American gun culture: a piece of jewelry that can land you in handcuffs. The allure is understandable—it’s a tiny, rebellious emblem of firepower, a conversation starter for range days, a bit of covert "full-auto" swagger.
: Under the National Firearms Act (NFA), the definition of a "machine gun" includes any part designed and intended solely to convert a weapon into a machine gun. Because a DIAS has no other function than this conversion, the part itself is legally considered a machine gun. The 1986 Cutoff