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 AR-15 builder. As an unfinished lower receiver, this component requires machining to complete the fire control pocket and trigger channel, placing the final assembly and legal compliance squarely in the hands of the end user. Manufactured by Polymer80, a brand recognized for advancing the 80% receiver market, the RL556V3 offers a polymer platform that balances structural integrity with weight reduction. This listing is for the lower receiver only, without jig or tooling, allowing you to select the specific finishing equipment that matches your workflow. The Rhino variant distinguishes itself through reinforced stress points and a textured grip profile, contributing to improved handling during the finishing process and subsequent use.

Overview

The Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only is a partially machined polymer component designed for AR-15 platform builds. It is manufactured from high-impact, glass-reinforced nylon polymer, offering a balance of rigidity and impact resistance. The receiver is engineered to accept standard AR-15 lower parts kits, buffer tubes, and pistol grip hardware after completion. The 80% designation indicates that the receiver is not a finished firearm and does not require serialization by a federal firearms licensee (FFL) when completed for personal use, provided local, state, and federal laws are followed. The Rhino model incorporates a reinforced takedown pin boss area and a flared magazine well for easier reloads once assembled. This receiver is compatible with standard AR-15 upper receivers, including those from major manufacturers such as Aero Precision, BCM, and Daniel Defense, provided the upper receiver is mil-spec dimensioned.

Features & Specs

• Material: Glass-reinforced nylon polymer with corrosion-resistant properties; weight approximately 7.2 ounces before finishing
• Compatibility: Accepts standard AR-15 LPK, buffer tube assembly, and pistol grip; mil-spec trigger group pocket dimensions after completion
• Design features: Integrated trigger guard, flared magazine well, textured grip surface, and reinforced front and rear takedown pin lugs
• Manufacturing: MIM (metal injection molded) insert for the rear takedown pin detent; precision-molded buffer tube threads compatible with standard carbine and rifle buffer systems
• Finish: Matte black textured exterior; internal surfaces require finishing to remove polymer webbing and complete fire control pocket to 0.300-inch depth

The Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only requires the user to drill three pin holes (trigger, hammer, safety selector) and machine the fire control pocket to depth. The receiver ships with a polymer jig rail alignment block for the trigger slot but does not include a drilling jig or end mill. Recommended finishing tools include a drill press or hand drill with a 0.125-inch bit for pin holes and a 1/4-inch end mill for pocket finishing. The receiver is designed to accept a standard AR-15 buffer retainer pin without modification.

Who It’s For

This product is intended for experienced firearm builders who possess the necessary tools, knowledge, and legal understanding to complete an 80% receiver in compliance with all applicable laws. It is not recommended for first-time builders who have not previously completed a polymer lower receiver, as the finishing process requires careful material removal to avoid compromising the trigger pocket walls. The Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only is suitable for hobbyists building a dedicated caliber-specific AR-15, such as 5.56 NATO, .300 Blackout, or 9mm with an appropriate magazine adapter block. It also suits those who prefer a lighter-weight lower receiver for competition or field use where polymer offers advantages over aluminum in weight and cold-weather handling. This receiver is not for individuals seeking a complete firearm or those who lack access to a drill press, vise, and proper measuring tools.

Shipping & FFL

This item is an unfinished receiver and does not require shipment to a Federal Firearms Licensee (FFL) for transfer. It can be shipped directly to your residential or business address within the United States, subject to state and local laws. However, you must be at least 18 years of age to purchase and receive this product. Some states, including but not limited to California, Connecticut, Hawaii, Illinois, Massachusetts, New Jersey, New York, Rhode Island, and Washington D.C., restrict or prohibit the possession, purchase, or completion of 80% receivers. It is your sole responsibility to verify that your local laws allow the ownership and finishing of unserialized firearm components. By purchasing the Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only, you confirm that you are legally eligible to own and complete this component in your jurisdiction. No returns or exchanges are accepted on unserialized receivers once shipped.