Auto Sear: What It Is and Why It’s Dangerous

An auto sear is a small mechanical device that can convert a semi-automatic firearm into a fully automatic weapon. Although compact in size, its impact is massive—turning legal guns into illegal machine guns with the potential to fire dozens of rounds in just seconds. Auto sears are highly regulated and, in many countries auto sear including the United States, strictly illegal for civilian use unless properly licensed.

What Does an Auto Sear Do?

In a semi-automatic firearm, the trigger must be pulled each time to fire a round. An auto sear changes that. Once installed, the firearm fires continuously as long as the trigger is held down. This turns a civilian firearm into a machine gun, drastically increasing the rate of fire and reducing control and accuracy.

Auto sears are often associated with handguns like Glocks but can be adapted to rifles and other firearms depending on the design. In many cases, they are referred to by various names—conversion switches, Glock switches, or simply “machine gun parts.”

Legal Status

Auto sears are classified as machine gun conversion devices. Under most national laws, including in the United States, they are considered the same as machine guns. This means:

• Possessing an auto sear without a proper license is illegal

• Installing one on a firearm is a federal offense

• Buying, selling, or even 3D-printing an auto sear can lead to serious criminal charges

The penalties for possession can include large fines and years of imprisonment.

Why They’re a Serious Concern

1. Public Safety Threat: Firearms with auto sears can fire up to 1,200 rounds per minute. In public spaces, such rapid fire makes them extremely deadly, especially in crowded areas.

2. Use in Crime: These devices are increasingly being used in violent crimes due to their compact size and ease of installation.

3. Hard to Detect: An auto sear is small—often no larger than a coin—making it easy to hide and transport. Some versions can be made using 3D printers, further complicating efforts to control their spread.

Law Enforcement and Public Awareness

Authorities worldwide are cracking down on the illegal use and distribution of auto sears. Police departments are being trained to identify firearms modified with these devices, and efforts are underway to trace their sources—whether imported or domestically made.

Public awareness campaigns are also being launched to help people understand the dangers of illegal firearm modifications and to encourage responsible gun ownership.

Final Words

An auto sear may look like a harmless metal part, but it carries enormous legal and safety risks. It transforms firearms into highly dangerous weapons with just a small adjustment. Staying informed, reporting suspicious behavior, and following the law are essential steps in keeping communities safe from the threat posed by illegal conversion devices.