RL556v3 80% AR15 Lower – Black | Polymer80
About this product
The Polymer80 RL556v3 is a black 80% AR-15 lower receiver designed for builders who want a lightweight, durable foundation for their rifle. This is our most consistent seller since we began stocking it in January 2026. It arrives unfinished, requiring standard machining to complete, and provides a solid polymer base that’s proven reliable for countless builds.
Key Highlights
- Constructed from high-strength, fiber-reinforced polymer for durability and reduced weight.
- Compatible with standard AR-15 parts kits and upper receivers.
- Includes integrated trigger guard and reinforced critical stress points.
- Jig and drill bits are required for completion (sold separately).
- We maintain a stock of 20+ units due to consistent, high demand.
Product Details
| Model | RL556v3 |
| Material | Fiber-Reinforced Polymer |
| Finish | Black |
| Compatibility | Mil-Spec AR-15 |
| Status | 80% Lower Receiver |
| Weight (measured) | 5.0 oz |
| Fire Control Pocket | Requires Machining |
| Trigger Guard | Integrated |
What Buyers Ask
What tools are needed to finish this lower?
You will need a drill press or router, a compatible jig (like the Polymer80 PF940v2 or RL556v3 jig), drill bits, and an end mill. Standard AR-15 armorer’s tools are required for final assembly with a parts kit.
Is this compatible with all AR-15 uppers?
Yes. The RL556v3 is designed to be compatible with standard mil-spec AR-15 upper receivers. We have not encountered fitment issues with in-spec uppers during our testing.
How does the polymer hold up compared to aluminum?
The fiber-reinforced construction provides significant strength at a fraction of the weight (5.0 oz). It handles the stresses of the fire control group and buffer tube effectively. For extreme-use applications, consider your specific requirements, but for most builds, it performs reliably.
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Specs at a glance
What's in the box
- RL556v3 80% AR15 Lower – Black | Polymer80