Building your own AR-15 lower receiver is a significant undertaking, requiring precision, patience, and a thorough understanding of firearms regulations. This guide focuses on the final steps of completing an 80% lower, emphasizing safety and legal compliance. Always prioritize safety and adhere to all local, state, and federal laws. This information is for educational purposes only and does not constitute legal advice.
Understanding the 80% Lower
An 80% lower receiver is an unfinished component that lacks the critical features required to be considered a firearm under federal law. The process of completing it involves milling, drilling, and potentially other machining operations to create the necessary fire control group pocket, trigger pin holes, and other essential components. Once completed, it becomes a regulated firearm.
Tools and Materials Needed
Before starting, ensure you have the necessary tools and materials. Improper tools can lead to an unsafe or non-functional lower receiver. This is not an exhaustive list, but it covers the essentials:
- 80% Lower Receiver: Choose a high-quality lower from a reputable manufacturer.
- Jig: A milling jig is crucial for accurate machining. The jig type will depend on your machining methods.
- Machining Equipment: This could include a milling machine, drill press, or other specialized tools depending on the jig and your chosen method.
- Drill Bits: Precisely sized drill bits are necessary for creating the trigger pin holes and other necessary holes.
- Files and Sandpaper: Used for smoothing and refining surfaces after machining.
- Protective Gear: Safety glasses, hearing protection, and a dust mask are essential to protect yourself from flying debris and metal dust.
- Cleaning Supplies: To remove metal shavings and debris after the process is complete.
Step-by-Step Finishing Process
The exact steps will vary slightly depending on the jig and machining methods used. However, the general process includes:
1. Preparing the 80% Lower
Begin by thoroughly cleaning the 80% lower receiver to remove any manufacturing debris. Inspect it for any imperfections or defects.
2. Securing the Jig
Carefully and securely mount the 80% lower into the chosen jig, ensuring it's properly aligned and clamped. Improper alignment can result in a non-functional or unsafe receiver.
3. Milling (if applicable)
If your jig requires milling, carefully follow the instructions for your specific jig and equipment. This step usually involves removing material to create the fire control group pocket and other essential features. Proceed slowly and meticulously to ensure accuracy.
4. Drilling
Use the appropriate drill bits to create all necessary holes, such as the trigger pin holes, takedown pin holes, and hammer pin holes. Use a drill press for maximum accuracy and control. Double-check the hole locations and sizes before drilling.
5. Deburring and Finishing
After machining, deburr all edges and holes with files and sandpaper to create smooth surfaces and prevent injuries. This step is crucial for a functional and safe firearm.
6. Cleaning and Inspection
Thoroughly clean the completed lower receiver to remove all metal shavings and debris. Carefully inspect the finished product for any defects or imperfections.
Legal Considerations
The completion of an 80% lower receiver brings it under the purview of federal and state firearms laws. You are responsible for understanding and complying with all applicable regulations. This includes registration requirements, background checks (where applicable), and any restrictions on ownership. Failure to comply can result in severe penalties.
Safety Precautions
Building a firearm requires a high level of responsibility and caution. Always:
- Follow all safety instructions provided with your tools and jig.
- Wear appropriate personal protective equipment (PPE).
- Work in a well-ventilated area.
- Dispose of metal shavings and debris properly.
- Never point a firearm at anything you are not willing to destroy.
This guide provides a general overview. Always consult detailed instructions specific to your chosen jig and tools. Remember, responsible gun ownership includes safe and legal practices. Improper construction can lead to malfunction and injury.
