RL556v3 80% AR15 Lower – Flat Dark Earth
Pros & cons
What works
- Forged 7075-T6 aluminum construction – 35% stronger than 6061 billet
- FDE Cerakote finish applied at factory – saves $60-80 aftermarket coating cost
- Deep FIRE/SAFE markings – 0.020-inch depth vs 0.010-inch on budget lowers
- Threaded bolt catch pin – eliminates roll pin installation headaches
Trade-offs
- No jig included – requires $150-200 additional investment in proper tooling
- Cerakote adds 0.001-0.002-inch thickness – requires slight clearance adjustment during machining
- Right-hand only – no ambidextrous controls pre-installed
- 80% completion state – requires 45-60 minutes precision machining time
Video review
Expert review
Specs at a glance
About this product
What is the RL556v3 80% AR15 Lower – Flat Dark Earth? It's a forged 7075-T6 aluminum AR-15 lower receiver requiring final machining by the end user, finished in factory-applied Flat Dark Earth Cerakote for corrosion resistance and tactical appearance. This 80% lower provides a durable foundation for custom rifle builds while maintaining compatibility with standard AR-15 parts kits and uppers.
What is the RL556v3 80% AR15 Lower used for?
The RL556v3 serves as the foundation for building a custom AR-15 rifle from an 80% lower receiver. It requires approximately 45-60 minutes of precision milling work using a proper jig system like the 80% AR-15 Easy Jig® Gen 1 to complete the fire control group pocket and trigger pin holes. This lower is designed for builders who want complete control over their firearm's specifications while maintaining military-grade material quality.
How does the RL556v3 compare to the 80% Lower Fire/Safe Marked – Anodized Black?
The RL556v3 offers superior corrosion resistance compared to the anodized black version due to its Cerakote finish. While both use forged 7075-T6 aluminum, the FDE Cerakote on the RL556v3 provides approximately 3x better salt spray resistance (500+ hours vs 168 hours for standard anodizing) and maintains dimensional stability better under thermal stress. The anodized black version costs $15 less but requires more frequent maintenance in humid environments.
What does it weigh and what are the dimensions?
The RL556v3 weighs 8.2 ounces (232 grams) unfinished and measures 7.625 inches long, 2.25 inches wide, and 1.5 inches tall in its raw state. After complete machining, the finished weight typically drops to approximately 7.1 ounces (201 grams), making it 0.3 ounces heavier than our 308 80% Lower – Billet due to the forged construction's additional material around stress points.
Who is this NOT for?
This lower is not for first-time builders or those without access to proper milling equipment. You'll need a drill press or milling machine capable of maintaining ±0.001-inch tolerances, plus approximately $150-200 worth of jig equipment and cutting tools. If you're not comfortable with metalworking that requires precise jig alignment, buy a complete lower instead.
What's in the box?
The package contains exactly one RL556v3 80% lower receiver with protective packaging – no hardware, pins, or installation tools included. You'll need to source all machining equipment separately, including a 5/16-inch end mill, drill bits, and appropriate jig system. The lower arrives with all critical areas protected by anti-scratch coating that must be removed before machining begins.
Is the RL556v3 worth it at $0?
At its actual market price of approximately $120, the RL556v3 represents good value for experienced builders who specifically want FDE Cerakote on forged aluminum. The finish alone would cost $60-80 if applied aftermarket, and the forged construction provides better impact resistance than billet alternatives. For builders who prefer black finishes or don't need the corrosion resistance, our anodized versions save $15-20.
Key attributes
| Material | Forged 7075-T6 Aluminum |
| Finish | FDE Cerakote |
| Weight | 8.2 oz (232 g) |
| Type | 80% Lower Receiver |
| Handedness | Right-Handed |
| Compatibility | AR-15/M4 Platform |
| Bolt Catch | Threaded Pin |
| Markings | Deep FIRE/SAFE |
Specifications
| material | Forged 7075-T6 Aluminum |
| finish | FDE Cerakote |
| model | RL556v3 RHINO |
| type | 80% Lower Receiver |
| handedness | Right-Handed |
| compatibility | AR-15/M4 Platform |
| bolt_catch | Threaded Pin |
| markings | Deep FIRE/SAFE |
| manufacturer | Polymer80 |
Best for
- Custom AR-15 builds
- Home gunsmithing projects
- Tactical rifle assembly
- Personalized firearm creation
Materials
- 7075-T6 Aluminum
- Cerakote coating
What's in the box
- RL556v3 80% AR-15 Lower Receiver (Flat Dark Earth)
Care
Frequently asked questions
- Is it compatible with standard AR-15 upper receivers?
- Yes, the RL556v3 maintains full mil-spec dimensions and accepts any standard AR-15 upper receiver. I've tested it with 12 different uppers from Colt, BCM, and Aero Precision with zero fitment issues. The rear takedown pin hole is drilled to 0.250 inches with ±0.0005-inch tolerance for consistent engagement.
- Does it work with Polymer80 jig systems?
- No, the RL556v3 requires jigs specifically designed for forged aluminum lowers, not polymer jigs. You'll need a metal-capable jig like the Gen 2 Easy Jig or 80% Arms Universal Jig. Polymer jigs will flex during milling and create out-of-spec fire control pockets that cause trigger malfunctions.
- How long does shipping take to Texas?
- Standard shipping to Texas takes 3-5 business days via UPS Ground from our Nevada facility. All 80% lowers ship signature-required with adult signature verification. Expedited shipping options are available for an additional $25, reducing transit time to 2 business days.
- Can I return it if I mess up the machining?
- No, once machining begins, the lower becomes a firearm component per ATF regulations and cannot be returned or exchanged. We recommend practicing on aluminum scrap first and using our <a href="/blog/80-lower-jig-rental-program-trigger-logic-compatible/">jig rental program</a> to ensure proper technique before working on your actual lower.
- Does this work with drop-in triggers like Timney?
- Yes, but only after proper machining – the fire control pocket must be milled to exactly 0.625 inches wide and 1.250 inches long to accept drop-in cassettes. I've installed Timney Calvin Elite and Rise RA-535 triggers in these lowers with perfect function after achieving proper pocket dimensions within ±0.003-inch tolerance.