The AR-10 platform, known for its powerful .308 Winchester (7.62x51mm NATO) cartridge, offers serious firepower. Building your own AR-10 from an 80% lower receiver, specifically a DPMS pattern lower, presents a unique opportunity for customization and cost savings. However, it's crucial to understand the legal implications, the build process, and the nuances of the DPMS pattern before you begin.
Understanding 80% Lower Receivers
An 80% lower receiver is a partially machined receiver blank. It lacks the critical features that legally define it as a firearm, such as the trigger housing, magazine well, and fire control group pocket. This means it's not considered a regulated firearm under federal law (in most jurisdictions; always check your local laws). Completing the machining to create a fully functional receiver is the responsibility of the builder.
The DPMS Pattern: A Key Distinction
Unlike the more common AR-15 pattern, the AR-10 market is fragmented, with multiple manufacturers using different receiver specifications. The DPMS pattern is one of the most prevalent. Choosing a DPMS pattern 80% lower means your upper receiver, bolt carrier group, and other components must also be compatible with this pattern. Using incompatible parts can lead to malfunctions or even dangerous situations.
Key Differences Between AR-15 and DPMS Patterns:
- Size and Dimensions: The AR-10 is significantly larger and heavier than the AR-15, reflecting the larger cartridge it fires.
- Receiver Specifications: The dimensions and features of the receiver differ substantially. Direct interchangeability is not possible.
- Bolt Carrier Group (BCG): AR-10 BCGs are larger and heavier than AR-15 BCGs, reflecting the increased recoil and power of the .308 round.
Building Your AR-10 80% Lower: A Step-by-Step Overview (Conceptual)
Disclaimer: Building a firearm involves complex machinery and potentially dangerous processes. Improper handling of tools or parts can result in injury or damage. This is a general overview and should not be considered a comprehensive guide. Always prioritize safety and consult reputable resources and professionals before attempting this process.
The process generally involves:
- Acquiring the 80% Lower: Purchase a DPMS pattern 80% lower receiver from a reputable supplier.
- Machining: This requires specialized tools and expertise. Jigs and templates are typically used to ensure accuracy. Improper machining can render the receiver unusable or dangerous.
- Completing the Receiver: This involves milling, drilling, and other processes to create the necessary features.
- Parts Sourcing: Source compatible upper receivers, BCGs, barrels, and other components. Ensure all parts are compatible with the DPMS pattern.
- Assembly: Carefully assemble all components, following the manufacturer's instructions and prioritizing safety.
Legal Considerations: Always Check Local and Federal Laws
The legality of 80% lowers varies by location. While federal regulations generally don't consider them firearms until completed, state and local laws can differ significantly. It’s essential to thoroughly research and understand the relevant laws in your area before purchasing or building an 80% lower receiver. Failure to comply with these laws can result in severe penalties.
Conclusion: A Powerful but Responsible Choice
Building an AR-10 from an 80% DPMS lower receiver offers a path to customization and potential cost savings. However, it's a process that demands precision, attention to detail, and a thorough understanding of the legal framework surrounding firearm ownership and construction. Always prioritize safety, legality, and responsible gun ownership. This information is for educational purposes only and does not constitute legal or technical advice.
