Polymer80 RL556V3 – RHINO 80% AR15 Lower Receiver ONLY

Product Overview

The Polymer80 RL556V3 RHINO is a groundbreaking 80% lower receiver designed for the AR-15 platform. This product is engineered for the DIY firearm enthusiast, the hobbyist builder seeking a personalized project, or anyone interested in understanding the mechanics of their rifle through hands-on completion. As an 80% lower, it is not a firearm as sold and requires machining and finishing to become a functional receiver, making it a popular choice for builders who value the process and the result. Its primary use is to serve as the foundational component for a custom AR-15 build, compatible with a vast array of standard AR-15 parts kits and uppers. The RL556V3 distinguishes itself by being crafted from a high-strength polymer composite, offering a unique alternative to traditional aluminum forgings.

Key Features

• Glass-Reinforced Nylon Composite Frame: Constructed from the same robust, fiber-reinforced polymer used in modern handgun frames, the RHINO provides exceptional durability and impact resistance while being significantly lighter than its aluminum counterparts.
• Simplified Machining for Beginners: Engineered for accessibility, this polymer lower is notably easier to mill, drill, and finish than an 80% aluminum lower. This allows builders with basic workshop tools and jigs to complete the project with greater confidence and less specialized equipment.
• Threadless Pistol Grip Design: An improvement over prior models, this integrated feature eliminates the traditional grip screw boss, reducing potential stress points within the receiver and creating a cleaner, more robust interface with your chosen pistol grip.
• RL556v3 Enhanced Design: This iteration includes refinements based on user feedback and engineering analysis, focusing on improving overall strength, ergonomics, and compatibility with standard AR-15 components and fire control groups.
• Semi-Automatic Action Compatibility: Designed to function as the core of a standard semi-automatic AR-15 rifle, it is built to reliably handle centerfire rifle cartridges like the .223 Remington and 5.56x45mm NATO when paired with a complete, quality parts kit and upper assembly.
• Standard Mil-Spec Dimensions: Maintains compatibility with the vast ecosystem of AR-15 aftermarket parts, including triggers, safeties, bolt catch assemblies, and buffer tubes, ensuring your build can be fully customized to your specifications.

Performance & Applications

The Polymer80 RL556V3 RHINO is suited for builders with specific goals in mind. Its design and material properties make it ideal for several focused applications.

The Lightweight Build Project: For hunters, hikers, or competitors looking to shave crucial ounces from their rifle, a completed RHINO build results in a noticeably lighter platform. When paired with a polymer or lightweight upper, the overall system weight reduction can be substantial without sacrificing the reliability expected from the AR-15 platform.

The Educational First Build: This lower is an excellent entry point for first-time builders. The relative ease of machining polymer reduces the intimidation factor and tooling requirements, allowing the builder to focus on learning the assembly process, the function of each component, and the fundamentals of firearm safety and maintenance in a hands-on manner.

The Customized Training Rifle: For individuals seeking a dedicated platform for high-round-count training, the RHINO’s durability and cost-effectiveness are key. Builders can configure it with dedicated training optics, a specific trigger, and other practice-focused components, creating a reliable tool that withstands rigorous use while keeping the investment in the lower receiver itself manageable.

About Polymer80

Polymer80 has established itself as a leader in the DIY firearms component market through a commitment to innovative engineering and material science. The company’s expertise is rooted in developing advanced polymer formulations that meet the stringent demands of modern firearm frames. Their products are not simple plastic copies; they are the result of extensive research into fiber reinforcement, stress modeling, and real-world testing. The RHINO lower leverages this same proprietary knowledge, applying handgun-proven polymer technology to the rifle platform. This approach demonstrates Polymer80’s authority in creating durable, functional components that empower the building community with new options and capabilities.

Why Buy From Blythes Sport Shop

Blythes Sport Shop, based in Valparaiso, IN, is a established retailer known for its commitment to providing enthusiasts with a serious selection of components and firearms. Their focus extends to supporting the building community with key parts like the Polymer80 RL556V3. When you order from Blythes, you’re dealing with a knowledgeable team that understands the products they sell, ensuring a straightforward purchasing process for items ranging from ammo to build kits. They serve as a reliable source for builders looking to acquire quality components.

Make Your Decision

The Polymer80 RL556V3 RHINO 80% Lower Receiver presents a clear choice for the AR-15 builder seeking a lightweight, user-friendly alternative to aluminum. Its reinforced polymer construction, simplified machining process, and proven design updates make it a compelling option for a first build or a specialized project. Consider your tools, your goals for the finished rifle, and your desire to work with a modern composite material. If a durable, lightweight foundation that simplifies the finishing process aligns with your build plan, the RHINO is a rational and innovative solution to complete your custom AR-15.

Technical Specifications

Manufacturer	Polymer80
Action Type	semi-automatic
Frame Material	polymer

Frequently Asked Questions