Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only

If you are looking to start a dedicated AR-15 build from the ground up, the Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only is a solid foundation that gives you the freedom to build exactly what you want. This 80% lower receiver is designed for the hands-on shooter who prefers to take the build process into their own hands. It requires some finishing work, but the payoff is a custom lower that matches your specific preferences. Whether you are assembling your first rifle or adding another platform to your collection, this Polymer80 unit delivers the ruggedness and modularity you expect from a quality 80% lower.

The Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only is machined from a high-strength polymer composite that stands up to regular use while keeping weight down. It is compatible with standard AR-15 parts kits and mil-spec buffer tubes, so you do not have to hunt for proprietary components. The integrated trigger guard and reinforced rear takedown lug add structural strength where it matters most. The lower accepts standard AR-15 magazines and works with both .223 Remington and 5.56 NATO uppers. This receiver is designed to be finished with basic tooling, making it a practical choice for builders at various skill levels.

Overview

The Polymer80 RL556V3, also known as the Rhino, is an 80% AR-15 lower receiver that comes uncompleted. This means the fire control pocket is not fully milled, and the trigger pin holes are not drilled. You finish the machining at home, giving you a receiver that is not serialized and does not require transfer through an FFL at the time of purchase. The Rhino series features a textured grip area, a flared magazine well for quicker reloads, and a reinforced front pivot pin area. It is a straightforward build platform that keeps the project in your hands from start to finish.

Features & Specs

• Manufactured by Polymer80 in the USA from impact-resistant polymer composite material that resists cracking and warping under normal shooting conditions.
• Compatible with standard AR-15 lower parts kits, mil-spec buffer tubes, and commercial-spec stocks and grips for broad aftermarket support.
• Integrated trigger guard eliminates the need for a separate part, and the ambidextrous bolt catch recess accommodates both left- and right-handed shooters.
• Reinforced rear takedown lug and front pivot pin boss add durability at high-stress points during firing cycles.
• Flared magazine well speeds reloads under stress, and the textured grip area provides a secure hold even with wet or gloved hands.

The lower receiver is designed for use with .223 Remington and 5.56 NATO chambers, and it accepts all standard AR-15 magazines. The overall dimensions are within mil-spec tolerances, ensuring a snug fit with most uppers. Weight is approximately 8.5 ounces, keeping your overall rifle build light. The RL556V3 – Rhino is a true 80% receiver that requires drilling of the trigger and hammer pin holes as well as milling of the fire control pocket to complete.

Who It’s For

This 80% lower is for the builder who wants to learn the mechanics of the AR-15 platform hands-on. It suits the home gunsmith who has basic tools like a drill press, a router or milling jig, and the patience to finish the receiver correctly. It is also a good choice for shooters who prefer to keep their firearm out of any registry by completing it themselves. Whether you are a first-time builder looking for an affordable entry point or an experienced hobbyist adding another customized rifle to your safe, the Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only gives you a blank canvas to work with. It is not a drop-in part; it requires time, attention, and proper tooling to complete.

Shipping & FFL

Because this is an 80% lower receiver and not a completed firearm, it can be shipped directly to your doorstep without the need for an FFL transfer at the time of purchase. However, you must be at least 18 years of age and comply with all applicable federal, state, and local laws regarding the possession and finishing of 80% receivers. Once you complete the machining and assemble the lower into a functional firearm, it becomes a regulated item under the Gun Control Act, and you must follow all laws regarding ownership, serialization, and transfer requirements in your jurisdiction. We do not provide legal advice, and it is your responsibility to ensure compliance with all laws before beginning your build. This product is sold as a raw component intended for finishing by the end user.