Polymer80 LR-308 80% Lower Receiver – .308

Product Overview

The Polymer80 LR-308 80% Lower Receiver is the foundational component for builders looking to create a customized, large-frame AR-platform rifle. Designed for the serious hobbyist, this receiver is a “blank” or unfinished part, requiring machining to be completed into a functional firearm component. It is engineered for the .308 Winchester/7.62x51mm NATO caliber, making it the core of a custom AR-10 build. Its primary use is for individuals who enjoy the hands-on process of gunsmithing, value the satisfaction of a personal build, and seek a lightweight alternative to traditional aluminum receivers. This product is ideal for experienced builders and, due to its user-friendly material, can also be a suitable project for first-time 80% builders who have done their research and understand the tools and process required.

Key Features

• Nylon-Reinforced Polymer Frame: Constructed from a proprietary, glass-reinforced polymer composite, this lower receiver offers a significant reduction in weight compared to aluminum counterparts while maintaining impressive durability and rigidity for reliable performance.
• .308/7.62 NATO Compatibility: Specifically machined to accept standard AR-10/.308 platform parts kits, upper receivers, and magazines, ensuring broad compatibility for your custom large-frame build.
• Optimized for Easy Machining: The polymer material is notably easier to drill and mill than aluminum, reducing wear on standard workshop tools and allowing for a more straightforward finishing process with a drill press or router jig.
• Lightweight Design: The polymer construction shaves critical ounces from your rifle’s overall weight, a key consideration for building a hunting rig or a rifle intended for extended carry.
• Pre-Machined Critical Areas: Essential features like the fire control group pocket, trigger pin holes, and buffer tower are pre-formed, providing a precise guide for the builder and simplifying the final machining steps.
• Reinforced Stress Points: Strategic engineering and reinforcement in high-stress areas, such as the buffer tube interface and pivot/take-down pin lugs, ensure the receiver can handle the sustained pressures of the .308 cartridge.

Performance & Applications

The completed Polymer80 LR-308 lower receiver serves as the legal frame of a firearm and, when paired with a quality barreled upper assembly and components, forms a fully functional AR-10. Its design supports a variety of specific applications.

Custom Hunting Platform: The lightweight nature of the polymer lower is a distinct advantage for hunters. By building your own AR-10, you can select a barrel length, contour, and optic that suit your specific game and terrain, all on a receiver that reduces overall weight for easier mobility in the field.

Dedicated Long-Range Precision Rifle: For shooters interested in long-range shooting or target competition, this receiver provides a stable foundation. Builders can install a match-grade trigger, a precision stock, and pair it with a heavy-profile barreled upper to create an accurate, customizable system capable of consistent performance at extended ranges.

Home-Based Gunsmithing Project: This product is fundamentally for the enthusiast who derives satisfaction from the fabrication process itself. It represents a hands-on educational project in firearm mechanics and manufacturing, resulting in a personalized rifle that reflects the builder’s own skill and component selection.

About Polymer80

Polymer80 is a recognized leader in the modern firearms ecosystem, specializing in innovative frame and receiver solutions. The company has built its reputation on a deep understanding of polymer engineering and firearm design principles. Their expertise is demonstrated through rigorous testing and development, focusing on creating products that meet specific performance criteria for durability, ergonomics, and compatibility. Polymer80’s commitment to the builder community is evident in their design philosophy, which prioritizes logical, user-friendly manufacturing processes without sacrificing strength or reliability. They have established authority in the market by consistently producing components that adhere to precise specifications, ensuring builders can complete their projects with confidence in the foundational part’s integrity.

Make Your Decision

The Polymer80 LR-308 80% Lower Receiver is a purposeful choice for the informed builder. It represents a commitment to a customized build process and a finished product with a unique weight advantage. Your decision should be based on your comfort with the required machining steps, your desire for a lightweight .308 platform, and your appreciation for the hands-on aspect of firearm assembly. Ensure you understand all local, state, and federal regulations regarding the purchase and completion of 80% receivers, and possess the proper tools, jig, and knowledge to finish the part safely and correctly. This receiver is a project component designed for those who value the journey of building as much as the final result.

Technical Specifications

Frequently Asked Questions