A Glock auto sear is an illegal device in most circumstances

A Glock auto sear — sometimes called a "full auto switch" or "auto sear" — is a small metal part designed to convert a semi-automatic Glock pistol into a fully automatic weapon. Federal law prohibits manufacturing, possessing, transferring, or importing auto sears without a specific license from the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF). Possession of one is a felony that carries a prison sentence of up to 10 years and fines up to $250,000, even if the device is never installed or used.

The ATF treats auto sears as machine gun parts under the National Firearms Act and the Firearm Owners Protection Act of 1986. This means the law does not distinguish between possessing the part itself and possessing a completed automatic weapon — the part alone is the crime. State laws often impose additional penalties on top of federal charges.

Key Takeaways

  • Possessing an auto sear is a federal felony punishable by up to 10 years in prison and $250,000 in fines, regardless of whether it is installed or used.
  • The ATF classifies auto sears as machine gun components, making them illegal to manufacture, buy, sell, or own without an extremely restricted federal license.
  • State and local laws add additional criminal penalties in most jurisdictions, and some states impose mandatory minimum sentences.
  • Law enforcement agencies actively investigate and prosecute auto sear cases, often discovering them during traffic stops, arrests for other crimes, or tips from the public.
  • Conviction results in a permanent felony record that affects employment, housing, voting rights, and future firearm ownership.

How the ATF defines and enforces the law

The ATF considers any device that allows a firearm to fire more than one round per trigger pull to be a machine gun, regardless of how it works or what it is called. An auto sear meets this definition because it disables the trigger reset mechanism, allowing the firing pin to strike the primer repeatedly as long as the trigger is held down.

The agency does not require proof that the device was actually installed or functional. Possession of the part in your home, vehicle, or on your person is sufficient for federal prosecution. The ATF has specialized units that investigate auto sear cases, and they often work with local police departments and the FBI on joint task forces.

Enforcement has increased significantly in recent years. The ATF publishes public service announcements warning about auto sears and actively monitors online marketplaces, social media, and gun shows for illegal sales. Many cases begin with a tip from the public or discovery during an unrelated traffic stop or arrest.

State and local penalties beyond federal law

While federal law sets the floor for prosecution, most states impose their own criminal statutes on machine gun parts. Some states classify auto sear possession as a separate felony distinct from federal charges, meaning you can be prosecuted in both state and federal court for the same conduct.

Several states impose mandatory minimum sentences for machine gun possession that exceed the federal minimum. For example, some jurisdictions require a minimum of 5 years in prison before any possibility of parole, and a few states have no parole option at all for this offense. Others add weapons enhancements that stack on top of the base sentence.

Local ordinances in major cities often add misdemeanor charges as well, though these are typically prosecuted alongside the felony charges rather than instead of them. The cumulative effect is that a single auto sear can result in multiple convictions and sentences that run consecutively rather than concurrently.

What happens during a federal investigation

ATF investigations into auto sear possession typically begin with a tip, a social media post, an online marketplace listing, or discovery during an arrest for an unrelated crime. Once the agency opens an investigation, agents may conduct surveillance, monitor communications, and coordinate with local law enforcement.

If agents believe they have probable cause, they will seek a search warrant from a federal judge. The warrant allows them to search your home, vehicle, and any other location where the device might be stored. During the search, agents document everything they find and photograph the scene.

After the search, the ATF sends the device to its laboratory for analysis to confirm it is indeed an auto sear. This process typically takes several weeks. Once confirmed, the case is referred to the U.S. Attorney's Office in your district for prosecution. You will be charged in federal court, and bail is often denied or set very high because the offense is considered serious.

Consequences beyond criminal penalties

A felony conviction for auto sear possession creates permanent collateral consequences that extend far beyond the prison sentence and fine. You will lose the right to vote in most states, either permanently or for a specified period. You become ineligible to hold a professional license in many fields, including law enforcement, security, healthcare, and education.

Employment becomes significantly more difficult. Most employers conduct background checks, and a felony conviction for a weapons offense is a disqualifying factor for the vast majority of jobs. Housing discrimination is legal in most states — landlords can refuse to rent to someone with a felony record. You also lose the right to possess any firearm for life under federal law.

If you are not a U.S. citizen, a conviction will trigger deportation proceedings. Even if you are a citizen, the conviction will appear on background checks for the rest of your life and cannot be sealed or expunged in federal court.

How people are typically caught

Most auto sear cases do not result from targeted investigations. Instead, they are discovered incidentally during other police activity. A traffic stop for a broken taillight leads to a search of the vehicle. An arrest for an unrelated crime results in a search of the home. A domestic violence call leads police to a residence where they find a firearm with an auto sear installed.

Online sales and social media posts account for a significant portion of cases. The ATF monitors marketplaces like Facebook, Instagram, and specialized gun forums. Undercover agents pose as buyers to identify sellers. Screenshots and tips from the public also lead to investigations.

Gun range employees and firearms instructors sometimes report suspicious activity to law enforcement. A person attempting to fire a Glock in full auto mode at a range, or asking questions about how to convert a firearm, may trigger a report that leads to an investigation.

Frequently Asked Questions

Is it legal to own an auto sear if I have a federal firearms license?

No. Even licensed firearms dealers and manufacturers cannot legally possess an auto sear unless they hold a specific SOT (Special Occupational Tax) license from the ATF and are manufacturing firearms for military or law enforcement contracts. A standard FFL does not permit auto sear possession. Violation is a felony regardless of licensing status.

What if I found an auto sear and did not know what it was?

Possession is still illegal, but you should contact the ATF or local law enforcement when ready and explain the situation. Turning it in voluntarily and cooperating with authorities may result in more lenient treatment than being caught with it. Do not attempt to install it, sell it, or hide it — that will make your legal situation significantly worse.

Can I be charged if the auto sear was in someone else's home and I did not know about it?

Constructive possession — knowing about the device and having the ability to control it — can be enough for a charge even if you did not own it. If you lived in a home where an auto sear was present and you knew about it, you could potentially be charged. If you genuinely did not know it was there, that is a defense, but you should consult an attorney when ready.

What is the difference between an auto sear and a bump stock?

A bump stock is a device that attaches to the outside of a rifle and uses recoil to increase the rate of fire. Bump stocks are illegal under federal law as of 2019. An auto sear is an internal part that converts a semi-automatic firearm into a fully automatic one. Both are illegal, but they work differently and are prosecuted under slightly different statutes.

If I am charged, should I talk to police without a lawyer?

No. Do not answer questions about an auto sear or any firearm without an attorney present. Anything you say can and will be used against you in court. Contact a criminal defense attorney when ready if you are arrested or questioned by law enforcement about this offense. Many attorneys offer free initial consultations.