A bump stock is a firearm accessory that uses the recoil of a semi-automatic rifle to make it fire faster, mimicking the rate of fire of a fully automatic weapon.

The device attaches between the rifle's stock (the part you hold against your shoulder) and the receiver (the main body of the gun). When you fire, the rifle recoils backward slightly. A bump stock uses a spring-loaded mechanism to let the barrel move forward and backward while your finger stays in contact with the trigger. This rapid back-and-forth motion causes the trigger to reset and fire again with each recoil cycle, producing a much faster rate of fire than a standard semi-automatic rifle.

Bump stocks became widely known after the 2017 Las Vegas shooting, which led to significant legal changes. In 2019, the U.S. Department of Justice classified bump stocks as machine gun parts under federal law, making them illegal to manufacture, sell, transfer, or possess. If you own one, federal law requires you to destroy it or turn it in to law enforcement.

Key Takeaways

  • A bump stock uses a rifle's recoil to speed up the firing rate of a semi-automatic weapon without converting it to fully automatic fire.
  • The device attaches to the stock and uses a spring mechanism to let the barrel move while your finger stays on the trigger.
  • Bump stocks have been illegal under federal law since 2019 and are classified as machine gun parts.
  • Possession of a bump stock is a federal crime, and owners are required to destroy or surrender them to law enforcement.

How the Mechanism Works

A bump stock has two main parts: a fixed outer stock that attaches to your shoulder, and an inner sleeve that holds the trigger group and moves freely. A spring connects these two pieces. When you fire the rifle, the recoil pushes the barrel and receiver backward inside the outer stock. The spring then pushes them forward again, which resets the trigger. Your finger, held in a fixed position, contacts the trigger as it resets, causing another shot to fire when ready.

This cycle repeats as long as you hold the trigger and keep steady pressure on the device. The result is a rate of fire that can reach 400 to 800 rounds per minute, depending on the specific bump stock model and the rifle it is attached to. This is much faster than a typical semi-automatic rifle, which fires one round per trigger pull at a rate of 45 to 60 rounds per minute.

Legal Status and Federal Ban

Bump stocks were legal to buy and sell for several years after they were first manufactured in the early 2000s. They were marketed as accessories that improved the shooting experience and were sold openly by firearms retailers and online vendors.

Following the 2017 Las Vegas shooting, where a bump stock was used, public and political pressure led to a review of the devices. In December 2018, President Trump directed the Department of Justice to ban bump stocks. In March 2019, the DOJ issued a final rule classifying bump stocks as machine gun parts under the National Firearms Act and the Firearm Owners Protection Act. This made them illegal to manufacture, sell, transfer, import, or possess. The ban took effect on March 26, 2019.

Owners of bump stocks were given a grace period to comply. The law required people to destroy their bump stocks or surrender them to law enforcement. Failure to do so is a federal crime that can result in criminal penalties.

State-Level Restrictions

In addition to the federal ban, several states have their own laws restricting or banning bump stocks. Some states banned them before the federal rule took effect, and others have maintained separate state-level prohibitions. State laws vary in how they define the devices and what penalties explore for possession.

If you live in a state with its own bump stock law, that state's restrictions may be more strict than federal law. You should check your state's current firearms regulations to understand what is and is not permitted in your area.

Why Bump Stocks Became Controversial

Bump stocks drew attention because they allowed semi-automatic rifles to fire at rates approaching those of fully automatic weapons, while technically remaining semi-automatic under the law. This created a legal gray area: the rifle itself was legal, but the accessory changed how it functioned.

Supporters of the ban argued that bump stocks defeated the purpose of the semi-automatic classification and allowed weapons to be used in ways the law did not intend. Opponents raised concerns about the scope of the ban and how it was implemented through executive action rather than legislation. Regardless of the debate, the ban is current federal law and is enforced by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF).

What Happened to Existing Bump Stocks

People who owned bump stocks before the ban had a compliance period to destroy them or turn them in. The ATF did not conduct widespread enforcement to locate and seize bump stocks from private owners, but possession remains illegal. Some owners destroyed their devices, while others turned them in to law enforcement agencies or gun ranges that collected them.

If you inherited a firearm with a bump stock or found one, you should remove the device and destroy it or contact your local law enforcement to surrender it. Keeping a bump stock in your possession violates federal law.

Frequently Asked Questions

Can I legally own a bump stock anywhere in the United States?

No. Bump stocks are illegal under federal law everywhere in the United States as of March 2019. Even in states without additional state-level bans, federal law prohibits possession. The only legal action is to destroy the device or surrender it to law enforcement.

What is the difference between a bump stock and a fully automatic weapon?

A fully automatic weapon fires continuously as long as the trigger is held down. A bump stock is an accessory that makes a semi-automatic rifle fire much faster by using recoil, but it still requires a separate trigger pull for each shot in the mechanical sense. However, the end result is similar enough that the federal government classified bump stocks as machine gun parts.

What happens if I am caught with a bump stock?

Possession of a bump stock is a federal crime. Penalties can include criminal fines and imprisonment. The exact sentence depends on the circumstances and whether it is a first offense. You should consult a lawyer if you have questions about your specific situation.

Are there legal alternatives to bump stocks?

No legal accessories replicate the function of a bump stock in the United States. Other shooting techniques and accessories exist, but anything designed to increase the rate of fire of a semi-automatic rifle to approach automatic fire rates would likely fall under the same federal ban.