Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only

The Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only represents a significant evolution in the 80% receiver market, offering the serious builder a precision-machined platform that bridges the gap between raw material and finished component. This RL556V3 variant is designed for those who demand the structural integrity of a fully polymer composite frame combined with the customizability afforded by the 80% completion process. As a true 80% lower receiver, it requires final machining of the fire control pocket and trigger housing to become a functional AR15 lower, giving the end user complete control over the final build specifications. The Rhino designation reflects Polymer80’s commitment to enhanced ergonomics and reinforced stress points, making this receiver a robust foundation for a wide range of AR15 pistol and rifle configurations.

Overview

The Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only is a direct result of Polymer80’s ongoing research into polymer composite strength and manufacturing tolerances. Unlike earlier 80% designs, this V3 iteration incorporates a redesigned rear takedown pin boss area and a reinforced buffer tube tower to better withstand the cyclic stresses of high-round-count shooting. The receiver is manufactured from a proprietary high-impact polymer blend that resists chemical degradation from common solvents and lubricants while maintaining dimensional stability across a wide temperature range. This lower receiver is compatible with all standard AR15 upper receivers, parts kits, and magazines, ensuring that builders have maximum flexibility when sourcing components for their project.

Features & Specs

• Proprietary polymer composite construction with glass-fiber reinforcement for enhanced tensile strength and impact resistance in the fire control and trigger pin areas
• Integrated rear takedown pin detent pocket and spring channel, eliminating the need for separate installation of these small parts during the final assembly phase
• Pre-drilled and reamed trigger and hammer pin holes to 0.154-inch diameter with a tolerance of +/- 0.001 inches, ensuring consistent trigger component alignment after completion
• Full-length metal trigger guard reinforcement insert molded into the polymer, preventing flex or breakage during aggressive shooting or when using oversized trigger guards
• Accepts all mil-spec AR15 lower parts kits, pistol grips, and buffer tubes; compatible with both standard and enhanced pivot/takedown pin sets
• Textured front and rear grip areas with raised checkering pattern for positive purchase under wet or gloved conditions

Who It’s For

This Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only is intended for the experienced firearms builder who possesses the necessary tools, jigs, and machining knowledge to complete an 80% lower receiver to a functional state. It is suitable for individuals who wish to construct a custom AR15 platform without the requirement of a serialized, FFL-transferred lower receiver, provided all applicable federal, state, and local laws are followed. The Rhino model is particularly well-suited for builders who prioritize weight reduction without sacrificing structural rigidity, as the polymer construction yields a lower receiver that is approximately 40 percent lighter than a standard 7075-T6 aluminum unit while still accommodating high-pressure cartridge loads. This receiver is not recommended for first-time builders without prior experience using a drill press, router, or dedicated 80% lower jig system, as the final machining steps require precision to ensure proper safety and function.

Shipping & FFL

This Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver Only is classified as a non-firearm component under current federal regulations and may be shipped directly to your residence or business address without requiring transfer through a Federal Firearms License (FFL) dealer. However, it is the sole responsibility of the purchaser to verify that ownership and possession of an 80% lower receiver is legal in their specific state, county, and municipality. Some jurisdictions, including but not limited to California, New York, New Jersey, Connecticut, Washington, and Washington D.C., have enacted laws that may restrict the purchase, possession, or completion of 80% receivers. By placing an order, you certify that you are in compliance with all applicable laws governing the acquisition and subsequent finishing of this component. Standard shipping rates apply, and delivery is typically within 5 to 10 business days via a common carrier with adult signature required. No returns or exchanges are accepted on 80% receivers due to the permanent modifications involved in the completion process.