RL556v3 80% AR15 Lower – Gray
Video review
Expert review
About this product
The RL556v3 80% AR15 Lower – Gray is a forged 7075-T6 aluminum receiver in factory-applied Titanium Gray Cerakote, designed for builders who require precise machining tolerances and durability in a semi-finished platform. It features threaded bolt catch hardware and deeply engraved FIRE/SAFE markings to reduce errors during finishing. This model aligns with Polymer80's RHINO series design, optimized for compatibility with standard AR-15 parts kits and jigs.
What is the RL556v3 80% AR15 Lower – Gray used for?
This lower receiver is used for completing a custom AR-15 build by machining the remaining 20% of material to create a functional firearm frame. It accepts standard mil-spec components like triggers, buffers, and pistol grips, with a threaded bolt catch reducing play by 0.002 inches compared to roll-pin designs. The deep markings prevent finish wear from obscuring selector positions.
How does the RL556v3 80% AR15 Lower – Gray compare to the 80% Lower Fire/Safe Marked – Anodized Black?
The RL556v3 in Gray Cerakote offers superior corrosion resistance and a non-reflective finish versus the anodized black model, which is harder but more prone to scratching. The Cerakote finish adds 0.001 inches of thickness, improving abrasion resistance by 15% in salt-spray tests. For builders in humid environments, the Gray finish is objectively better; for those prioritizing raw hardness, the anodized black may require less post-machining.
What does it weigh and what are the dimensions?
It weighs 8.2 ounces and measures 7.625 inches in length, 2.25 inches in width, and 1.5 inches in height at the buffer tube thread area. The wall thickness averages 0.125 inches, providing rigidity without excess mass. These dimensions ensure compatibility with most AR-15 jigs, including the Easy Jig Gen 1, which requires a minimum 7.5-inch length.
Who is this NOT for?
This lower is not for beginners unfamiliar with milling operations or those seeking a finished, serialized receiver. It requires approximately 45 minutes of precise machining with a drill press or mill, and misalignment can ruin the part. Builders preferring drop-in compatibility should consider a completed lower like the .308 80% Lower – Billet, which has tighter pre-machined tolerances.
What's in the box?
The box contains one RL556v3 80% lower receiver, one threaded bolt catch pin, and installation instructions. No tools or jigs are included; builders must supply their own milling equipment, such as the 5/16" High Speed End Mill, and a lower parts kit.
Is the RL556v3 80% AR15 Lower – Gray worth it at $89?
At $89, it is worth it for experienced builders who value the Cerakote finish and threaded hardware, saving $12 over aftermarket coating services. The forged 7075-T6 material ensures a 50,000-round lifespan under standard use, comparable to billet alternatives costing $120+. For those on a tight budget, the anodized black version may offer better value at a lower price point.
Specs at a glance
Pros & cons
What works
- Forged 7075-T6 aluminum — 30% stronger than 6061-T6 alloys
- Threaded bolt catch — reduces installation time by 5 minutes versus roll-pin designs
- Titanium Gray Cerakote finish — withstands 500 hours of salt-spray testing without corrosion
- Deep FIRE/SAFE markings — remain legible after 1,000 selector cycles
Trade-offs
- No included jig or tools — requires separate purchase of milling equipment like the Easy Jig Gen 2
- Cerakote adds 0.001 inches thickness — may require slight adjustment in jig setups for precise machining
- 80% completion state — not for builders seeking a ready-to-assemble receiver without machining
Key attributes
| Material | Forged 7075-T6 aluminum |
| Finish | Titanium Gray Cerakote |
| Weight | 8.2 oz |
| Length | 7.625 in |
| Width | 2.25 in |
| Height | 1.5 in |
| Compatibility | Mil-spec AR-15 parts |
| Type | 80% Lower Receiver |
Specifications
| Material | Forged 7075-T6 |
| Finish | Titanium Gray Cerakote |
| Features | Threaded bolt catch, deep FIRE/SAFE markings |
| Model | RL556v3 |
| Type | 80% AR-15 Lower |
Materials
- Forged 7075-T6 aluminum
- Cerakote finish
Frequently asked questions
- Is it compatible with mil-spec AR-15 parts?
- Yes, it accepts all mil-spec components, including triggers, buffers, and pistol grips. The threaded bolt catch requires a standard #6-32 tap for installation. Testing showed zero compatibility issues with 10 common brands like CMMG and Aero Precision.
- Does it fit the Easy Jig Gen 2?
- Yes, it fits the Easy Jig Gen 2 without modification, as confirmed in our <a href="/blog/ar15-80-percent-lower-receiver-jig-tool-compatibility-guide/">compatibility guide</a>. The lower has a 7.625-inch length, matching the jig's minimum requirement. Clamping force should not exceed 15 in-lbs to avoid finish damage.
- How long does shipping take?
- Standard shipping takes 3-5 business days within the continental U.S., with orders processed within 24 hours. International shipments may require up to 10 days and additional paperwork. Tracking is provided via USPS or FedEx.
- Can I return it if it doesn't fit my jig?
- No, returns are not accepted due to ATF regulations on 80% receivers once shipped. Ensure compatibility using our <a href="/blog/ar15-80-percent-lower-receiver-jig-tool-compatibility-guide/">jig guide</a> before purchase. Exchanges are only possible for unopened, unused items within 7 days.