Understanding the AR-15 Selector Switch
Physical Description
The selector switch, sometimes referred to as a “safety” (though its function is far more nuanced than just safety), is a small, yet critically important, control on the AR-15. Physically, it’s a small lever, typically located on the left side of the receiver, above the trigger. The selector is usually made of metal, often steel or aluminum, and designed for durability and ease of manipulation.
The selector switch has distinct positions, clearly marked with either letters or symbols: “Safe,” “Semi-auto,” and, in the case of rifles with the full-auto capability (which, it’s important to reiterate, are highly restricted), “Full-auto.” Each position dictates the rifle’s firing behavior. The switch is manipulated by the shooter’s thumb, allowing for quick and easy adjustments.
Mechanical Function of the Selector Switch
The selector’s primary mechanical function is to control the interaction between the trigger mechanism and the sear. The sear is a small, precisely machined component that holds the hammer back in a cocked position, preventing the rifle from firing until the trigger is pulled. The selector switch physically blocks the movement of specific components within the trigger mechanism depending on its position.
In the “Safe” position, the selector physically blocks the trigger, preventing it from being pulled and thus preventing the firing cycle from initiating. In “Semi-auto,” the selector allows the trigger to function, releasing the hammer and firing a single round with each trigger pull. The “Full-auto” setting, in rifles so equipped, allows the firing mechanism to continue firing rounds as long as the trigger is held down.
Civilian vs. Military
The differences between a civilian AR-15 and a military-spec AR-15 hinge on this selector switch. Civilian AR-15s are designed and manufactured to be semi-automatic only. They are built with internal components that prevent full-auto firing, or lack the full auto selector switch. Military-spec AR-15s, on the other hand, are often designed for full-auto fire, although it is important to remember that the receiver must also be manufactured in a way that it is able to handle full auto. These military rifles feature internal components, including the selector switch, designed to facilitate continuous firing.
Semi-Automatic Versus Full-Automatic: Delving into the Mechanisms
Semi-Automatic Functionality
Let’s break down the mechanics of each firing mode. In a semi-automatic AR-15, the system is designed to fire one round per trigger pull. When the trigger is depressed, the hammer strikes the firing pin, which in turn strikes the primer of the cartridge, igniting the propellant. The expanding gases generated by the burning propellant drive the bolt rearward, extracting and ejecting the spent casing. Simultaneously, the bolt picks up a new cartridge from the magazine, and as it travels forward, it chambers the new round. As the bolt returns to battery, it re-cocks the hammer. The disconnector, a critical component, then engages, ensuring that the hammer is caught by the sear. As long as the trigger is not released, the firearm remains in a ready-to-fire state. Only when the trigger is released can it reset and the hammer be released again with a subsequent trigger pull. This cycle repeats with each trigger pull.
Full-Automatic Functionality
The key difference in function between the semi-auto and full-auto setting lies in the relationship between the trigger and the sear. The semi-automatic AR-15 incorporates a disconnector, which, as described above, releases the hammer after the trigger is pulled. The disconnector is disabled in the full-auto system. This design allows the hammer to repeatedly strike the firing pin and fire rounds with a single trigger pull.
In a full-automatic AR-15, when the trigger is pulled, the sear and disconnector are disabled. The hammer continues to be released, striking the firing pin and chambering and firing rounds continuously. The rate of fire is dictated by factors such as the firearm’s design, the ammunition used, and the mechanical characteristics of the system. Full-auto AR-15s can typically fire hundreds of rounds per minute, creating a sustained stream of projectiles.
Core Differences
It is important to highlight the core difference between these two firing mechanisms: control. In semi-automatic, the shooter controls each individual shot. In full-automatic, the shooter controls the initiation of fire and the cessation of fire, but the weapon itself controls the rate of fire and the number of rounds fired per trigger pull.
The Legal Landscape: National Firearms Act and the Restrictions
Introduction to the NFA
The legal environment surrounding full-auto firearms in the United States is exceptionally complex and tightly regulated, primarily through the National Firearms Act (NFA) of 1934. This landmark legislation was enacted in response to the proliferation of automatic weapons and other dangerous devices.
Definition of “Machine Gun”
The NFA defines a “machine gun” as “any weapon which shoots, is designed to shoot, or can be readily restored to shoot, automatically more than one shot, without manual reloading, by a single function of the trigger.” This definition encompasses any firearm capable of full-auto fire.
Legality in the US
The implications of the NFA are substantial. The possession of a machine gun by a private citizen is severely restricted. The general rule is that it must have been legally manufactured before 1986, registered with the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), and transferred through a specific, rigorous process. This process includes a background check, the payment of a significant tax, and potential inspections. The supply of transferable full-auto AR-15s is limited by the 1986 ban, making these weapons highly sought after and incredibly expensive.
The legality of owning a full-auto AR-15 varies from state to state, but in general, the federal regulations are paramount. State laws cannot supersede federal law. Any attempt to alter an existing AR-15 to achieve full-auto functionality without adhering to these regulations is a violation of federal law, regardless of the state you reside in.
Consequences of Illegal Modifications
Unauthorized modifications to any firearm, including the AR-15, to full-auto functionality can have grave consequences. Penalties can include severe fines, imprisonment, and the forfeiture of the firearm. Federal law enforcement takes the illegal modification, possession, or transfer of a machine gun seriously.
Aftermarket Options and Modifications (With Critical Legal Cautions)
Disclaimer
**Disclaimer: Under US federal law, it is illegal to modify an AR-15 to full-auto status unless it meets specific legal requirements. The information in this section is for educational purposes only and should not be construed as an endorsement or encouragement of any illegal activity.**
Legal Restrictions on Altering
Within the AR-15 world, there are a multitude of modifications available to enhance performance, customization, and aesthetics. However, regarding the full-auto aspect, it’s crucial to reiterate the legal limitations. Any alteration to an AR-15 to achieve full-auto functionality is strictly prohibited unless you are in possession of a legally transferable machine gun and have completed the extensive registration and transfer process.
Legal Aftermarket Modifications
Focusing on **legal** aftermarket modifications, owners can explore a variety of avenues. These modifications should never affect the core function of the selector switch to allow for full-auto. Many owners choose to change handguards, stocks, grips, triggers, optics, and other accessories. These modifications can improve the ergonomics, accuracy, and overall user experience.
Remember that any modifications can impact the firearm’s reliability and safety. It’s always best to seek guidance from qualified gunsmiths and manufacturers.
Safety Considerations
Whether you are handling a semi-automatic AR-15 or any other firearm, safety should always be the top priority. The AR-15, like any firearm, is a powerful tool and must be treated with respect.
Always follow these fundamental safety rules:
- Treat every firearm as if it were loaded.
- Never point the muzzle at anything you are not willing to destroy.
- Keep your finger off the trigger until you are ready to fire.
- Be sure of your target and what is beyond it.
Responsible gun ownership is essential. This includes storing firearms securely, understanding the laws in your jurisdiction, and taking the time to learn and practice safe gun handling techniques. Proper training is also critical. Taking courses in safe gun handling, marksmanship, and firearm maintenance will increase your comfort and competence with your weapon.
Conclusion
The AR-15 full auto selector switch is a critical component that governs the functionality of the firearm. While full-auto operation is a fascinating concept, its legality is heavily restricted, governed by the NFA. Understanding the mechanics and legal implications is crucial for responsible gun ownership and compliance with the law.
As a firearms enthusiast, you must be aware of the laws in your state. Remember to seek proper training, practice safe gun handling techniques, and comply with all applicable laws.
By focusing on safety, responsibility, and legal compliance, you can ensure you have a safe and rewarding experience with firearms.
