Introduction:
Building your own firearm can be a rewarding experience, offering a level of customization and understanding unavailable with commercially produced guns. One popular route involves completing an 80% lower receiver, a partially machined block of metal that requires further work to become a functional firearm lower receiver. This guide provides a comprehensive overview of the process, safety precautions, and legal considerations involved in completing an 80% lower. Remember, always prioritize safety and legality throughout this process. Understanding and adhering to all applicable federal, state, and local laws is crucial. Failure to do so can result in serious legal consequences.
Understanding 80% Lowers
An 80% lower is an unfinished receiver that lacks the critical components necessary to function as a firearm. The "80%" refers to the percentage of machining already completed by the manufacturer. This incomplete state allows it to bypass certain regulations that apply to fully manufactured firearms. However, completing the lower brings it into compliance with those regulations, making it subject to all applicable laws, including registration requirements in some jurisdictions.
Types of 80% Lowers
80% lowers are available in various materials, including aluminum and polymer. Aluminum lowers are generally more durable but heavier, while polymer lowers are lighter but might be less resistant to wear and tear. They also come in different styles, such as AR-15 lowers (the most common type), and others designed for different platforms.
Tools and Materials Needed
Completing an 80% lower requires specialized tools and equipment. The precise tools needed depend on the chosen method (e.g., jig, milling machine) but generally include:
- Jig (recommended for beginners): A jig is a crucial tool providing accurate alignment and support during the milling process. Different jigs exist depending on the chosen method.
- Milling Machine (or alternative): A milling machine offers precision, but a drill press with specialized bits can also be used (requires more skill and caution).
- End Mills: These are essential for machining the receiver. Sizes vary depending on the specific 80% lower and jig used.
- Drill Bits: Necessary for pre-drilling holes and potentially other steps, depending on the jig and lower.
- Clamps: Securely hold the 80% lower in place during machining.
- Safety Glasses and Hearing Protection: Absolutely essential to protect your eyes and ears during the process.
- Appropriate Lubricant: Facilitates machining and prevents overheating.
- Cleaning Supplies: To clean the completed lower.
The Completion Process: A Step-by-Step Guide
This guide provides a general overview. Always follow the instructions provided with your specific 80% lower and jig.
Step 1: Preparation
Carefully review the instructions for your specific 80% lower and jig. Gather all necessary tools and materials. Ensure the work area is clean, well-lit, and free from obstructions. Wear safety glasses and hearing protection at all times.
Step 2: Securing the Lower
Securely clamp the 80% lower into the jig according to the manufacturer's instructions. Ensure the lower is properly aligned and firmly held to prevent movement during machining.
Step 3: Milling (or Drilling and Filing)
This is the most critical step. Using the appropriate tools and bits, carefully mill (or drill and file) the receiver according to the instructions provided with your jig and 80% lower. Take your time, maintain consistent pressure, and avoid rushing. Inaccurate machining can render the receiver unusable or unsafe.
Step 4: De-burring and Cleaning
Once all machining is complete, carefully de-burr all edges and surfaces to remove any sharp or rough areas. Clean the completed lower thoroughly to remove any metal shavings or debris.
Step 5: Final Inspection
Before assembling the lower, conduct a thorough inspection to ensure all components are properly machined and aligned. Any imperfections could compromise the safety and functionality of the firearm.
Legal Considerations and Safety Precautions
Legality: Laws regarding 80% lowers vary significantly by state and locality. Some jurisdictions may require registration, while others may have outright bans. It is your responsibility to understand and comply with all applicable laws before starting this process. Consult legal counsel or your local authorities if you have any questions or uncertainties.
Safety: Working with machinery and tools requires utmost care. Always follow safety guidelines provided with your equipment. Never operate machinery while tired, distracted, or under the influence of drugs or alcohol. Improper handling can lead to serious injury.
Conclusion:
Completing an 80% lower receiver is a complex process that requires precision, skill, and a deep understanding of safety and legal requirements. While it offers a degree of customization and potential cost savings, it is not a project for beginners. Prioritize thorough research, careful planning, and adherence to all safety and legal protocols. Remember, responsible gun ownership begins with understanding and respecting the laws and safe handling of firearms.