Building your own AR-15 lower receiver can be a rewarding experience, allowing for customization and a deeper understanding of your firearm. This guide will walk you through the process, covering everything from the necessary tools and parts to safety considerations and legal compliance. Remember, always prioritize safety and adhere to all applicable local, state, and federal laws. This guide assumes you have a basic understanding of firearms safety and handling.
Choosing Your Lower Receiver
The AR-15 lower receiver is the serialized part of the rifle, legally defining it as a firearm. Therefore, choosing the right lower is crucial.
Types of Lower Receivers
- Stripped Lower Receivers: These are the most common type, requiring you to install all the internal parts. They are generally less expensive than complete lowers.
- Complete Lowers: These come with all the internal parts pre-installed, simplifying the build process. However, they cost more.
- 80% Lowers: These are partially machined receivers requiring additional work to complete the receiver. They often require specialized tools and knowledge. Legal implications vary by location, so research your local laws thoroughly before purchasing an 80% lower.
Material Considerations
Most AR-15 lowers are made from 7075-T6 aluminum, a strong and durable material. However, some are made from other materials like polymer or forged steel. Aluminum is the most common and generally preferred choice for its balance of strength and weight.
Key Features to Consider
- Compatibility: Ensure your chosen lower receiver is compatible with the other parts you plan to use. Different manufacturers may have slight variations.
- Finish: Anodized finishes are common and provide corrosion resistance. Cerakote finishes offer enhanced durability and customization options.
- Features: Some lowers feature integrated accessories, like picatinny rails or ambidextrous controls.
Gathering Your Tools and Parts
Before you begin, gather all the necessary tools and parts. A missing part or tool can significantly delay your project.
Essential Tools:
- Roll Pin Punch Set: Various sizes for installing and removing roll pins.
- Armorer's Wrench: For tightening and loosening castle nuts.
- Hammer: A standard ball-peen hammer will suffice.
- Punch Set (Various Sizes): For alignment and assembly.
- Torque Wrench: Crucial for proper torque values on screws and fasteners.
- Screw Driver Set (Various Sizes): Philips and flathead.
Essential Parts (Beyond the Lower Receiver):
- Upper Receiver: The upper receiver houses the barrel and bolt carrier group.
- Buffer Tube: This houses the buffer spring and buffer.
- Buffer Spring and Buffer: These help manage recoil.
- Grip: Provides a comfortable hold.
- Trigger Assembly: The heart of the firing mechanism.
- Safety Selector: Controls the firing modes of the weapon.
- Pistol Grip Screws: Secure the grip to the lower receiver.
- Magazine Catch: Releases the magazine.
- Bolt Catch: Locks the bolt to the rear.
- Hammer Pin: Connects the hammer to the trigger.
- Trigger Pin: Connects the trigger to the receiver.
- Takedown Pins: Used to disassemble the weapon.
- Small Parts Kit: Includes various pins, springs, and other small components.
Step-by-Step AR-15 Lower Build
This section provides a general overview. Always consult your specific manufacturer's instructions and reference videos for detailed guidance. Safety is paramount.
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Install the Hammer and Trigger Pins: Using the correct punches, carefully install the hammer and trigger pins into the lower receiver.
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Install the Safety Selector: Insert the safety selector into its designated slots.
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Install the Bolt Catch and Magazine Catch: Insert the bolt catch and magazine catch into their respective positions.
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Install the Trigger Assembly: Carefully assemble the trigger assembly, ensuring everything is properly aligned.
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Install the Grip: Attach the pistol grip using screws.
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Install the Buffer Tube: Attach the buffer tube to the rear of the lower receiver.
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Attach the Upper Receiver: Align the upper and lower receivers, and install the takedown pins.
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Install the Bolt Carrier Group (BCG): Insert the BCG into the upper receiver. This is usually the final step before test firing.
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Test Fire (At a Gun Range): Always perform a test fire at a properly supervised gun range with a qualified instructor if you lack previous experience with firearms assembly. Ensure your firearm is completely assembled and the safety is engaged.
Legal Considerations
Disclaimer: This information is for educational purposes only. Always check and comply with all local, state, and federal laws regarding firearm ownership and assembly. Regulations vary significantly by location, and failure to comply can lead to serious legal consequences. It is highly recommended that you consult with a legal professional specializing in firearms law before undertaking any AR-15 build.
Safety Precautions
- Always handle firearms responsibly: Keep the firearm pointed in a safe direction at all times.
- Never handle loaded firearms carelessly: Handle your firearm as if it were always loaded.
- Use appropriate eye and ear protection: Always use eye and ear protection when handling firearms.
- Regularly inspect your firearm: Ensure all parts are functioning correctly before each use.
- Properly store your firearm: Store your firearm securely and unloaded, out of reach of unauthorized individuals.
Building an AR-15 lower receiver requires attention to detail, meticulous assembly, and a comprehensive understanding of firearms safety and relevant regulations. Following these steps and prioritising safety will help ensure a successful and enjoyable build. Remember to always check local laws before proceeding.