Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only

The Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only represents a precision-engineered foundation for the custom builder who demands durability and exacting tolerances. Manufactured by Polymer80, a recognized leader in the 80% receiver market, this lower receiver is designed for the AR15 platform and offers a robust polymer construction that resists impact, chemicals, and environmental stress. As an 80% receiver, it requires final machining and assembly by the end user, providing the flexibility to create a firearm that meets your specific configuration requirements without the need for a serialized transfer in most jurisdictions. The RL556V3 – Rhino 80% AR15 Lower Receiver Only is compatible with standard AR15 upper receivers, parts kits, and accessories, making it a versatile starting point for a wide range of builds.

Overview

The Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only is a third-generation 80% lower that incorporates several design refinements over previous iterations. The “Rhino” designation refers to the integrated front and rear takedown pin detent recesses, which simplify assembly by eliminating the need for standard detent pins. The receiver body is injection-molded from a proprietary high-impact polymer blend that is reinforced in critical stress areas, including the buffer tube tower and trigger pocket. This model is designed to accept all mil-spec AR15 lower parts kits and is compatible with both standard and enhanced trigger groups. The RL556V3 – Rhino 80% AR15 Lower Receiver Only is sold as a non-functional blank that requires drilling of the trigger pin holes, selector lever hole, and fire control pocket, as well as the removal of the rear takedown pin lug and trigger guard. A complete instruction set with jigs is available separately from the manufacturer.

Features & Specs

• Material and Construction: High-impact reinforced polymer with glass-fiber filler for enhanced rigidity and dimensional stability. The receiver is molded to mil-spec dimensions with a tolerance of +/- 0.002 inches in critical interfaces. The polymer formulation is UV-stable and resistant to common solvents and lubricants used in firearm maintenance.
• Design Specifications: The RL556V3 – Rhino 80% AR15 Lower Receiver Only features a flared magazine well for faster reloads, an integral trigger guard with a 0.35-inch clearance for gloved use, and a reinforced buffer tube tower with a 7075-T6 aluminum threaded insert. The receiver weighs 7.2 ounces and accepts all standard AR15 stocks, grips, and buffer systems.
• Compatibility and Fit: Designed exclusively for the AR15 platform, this lower receiver is compatible with all mil-spec upper receivers from manufacturers such as BCM, Aero Precision, and Colt. The trigger pocket is cut to accept standard mil-spec triggers as well as cassette-style drop-in units. The Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only uses a standard AR15 magazine catch and bolt catch.

Who It’s For

The Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only is intended for experienced builders who possess the necessary tools, skills, and knowledge to complete an 80% receiver. This product is not suitable for first-time firearm assemblers or individuals without access to a drill press, router, and appropriate jigs. The RL556V3 – Rhino 80% AR15 Lower Receiver Only is designed for shooters who prioritize customization and want to create a lower receiver with specific trigger, stock, and grip configurations that may not be available in complete factory rifles. It is also a popular choice for those who want to build a dedicated competition, home defense, or recreational AR15 without purchasing a serialized receiver. This product is not intended for use in fully automatic configurations, and all local, state, and federal laws regarding the manufacture of firearms must be followed.

Shipping & FFL

This Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only is classified as a non-firearm item under federal law and does not require transfer through a Federal Firearms License (FFL) dealer for shipment. However, it is the responsibility of the purchaser to verify that possession and completion of this 80% receiver are legal in their state, county, and municipality. Some states, including but not limited to California, New York, New Jersey, Connecticut, Maryland, Hawaii, and Washington D.C., have specific regulations or outright prohibitions regarding 80% receivers. By purchasing this Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only, you acknowledge that you are legally allowed to own and complete this product in your jurisdiction. We ship via UPS Ground to all eligible states, and signature may be required at our discretion. No returns or exchanges are accepted on completed or modified receivers.