Bump Fire

What is Bump Fire?

Bump fire is a shooting technique that uses the recoil energy of a semi-automatic rifle to rapidly reset the trigger, allowing the firearm to fire multiple rounds in rapid succession with a single pull of the trigger finger. This technique can achieve rates of fire typically between 400-800 rounds per minute, though the actual rate varies based on the specific rifle configuration and shooter technique.

How Bump Fire Works

The technique relies on the physics of recoil in a semi-automatic firearm. When you fire one shot, the rifle moves backward into your shoulder. In bump firing, you hold your trigger finger stationary while allowing the rifle to move forward and backward freely. The forward pressure from your support hand causes the trigger to reset and contact your finger again, firing another round. This creates a cycle that continues as long as you maintain proper pressure and positioning.

Bump Fire Stocks and Legal Status

A bump stock is an accessory designed to facilitate this technique mechanically. Following the 2017 Las Vegas mass shooting, the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) reclassified bump stocks as machine gun components under federal law. The ban bump stocks rule went into effect in March 2019, making possession unlawful.

In 2024, the Supreme Court ruled in Garland v. Cargill that bump stocks do not meet the statutory definition of a machine gun, as they still require a single function of the trigger for each shot fired. This decision effectively overturned the bump fire stock ban, though individual state laws may still prohibit these devices.

Relevance for AR-15 Builders

When configuring your build on the AR15 Outfitters builder, understanding bump fire helps you make informed decisions about:

• Buffer weight selection: Heavier buffers typically reduce the rifle’s ability to bump fire
• Gas system tuning: Over-gassed rifles are more prone to unintentional bump firing
• Trigger selection: Competition triggers with extremely light pull weights (under 3.5 pounds) may increase susceptibility to bump firing

Most builders aim to minimize unintentional bump fire through proper component selection and gas system tuning for improved accuracy and control.