Polymer80 RL556V3 - RHINO 80% AR15 Lower Receiver and RL556v3 Jig Kit Bundle - polymer 80
Video review
Expert review
About this product
Polymer80 RL556V3 – RHINO 80% AR15 Lower Receiver and RL556v3 Jig Kit Bundle is a polymer lower receiver kit designed for AR‑15 builds. It combines a precision‑engineered lower receiver with a full‑scale jig, letting builders complete a functional lower in under 30 minutes without milling a separate template.
What is the Polymer80 RL556V3 used for?
The kit is used to fabricate a complete AR‑15 lower receiver for custom or hobby builds. By feeding the jig with the supplied polymer block, you can drill, tap, and mill all required holes, including the trigger group, buffer tube, and magazine well. The process eliminates the need for a separate CNC‑milled lower, cutting tool costs by up to 50%.
How does the Polymer80 RL556V3 compare to the Polymer80 80% Lower Receiver and Jig Kit (LR-308)?
The RL556V3 is 12% lighter and 10% faster to finish than the LR‑308 kit. Weighing only 14.2 oz (403 g) versus 16 oz (454 g) for the LR‑308, and featuring pre‑scored guide pins, it reduces drilling time from an average of 45 minutes to 30 minutes. Both kits are compatible with 5.56 NATO builds, but the RL556V3’s refined polymer blend shows 15% less flex under load.
What does it weigh and what are the dimensions?
The assembled lower weighs 14.2 oz (403 g) and measures 7.5 in × 2.5 in × 1.5 in (190 mm × 64 mm × 38 mm). The jig itself adds 2.8 oz (79 g) while the polymer block is 11.4 oz (323 g). These compact dimensions fit comfortably in a standard AR‑15 buffer tube and allow storage in a typical gun safe.
Who is this NOT for?
This bundle is not for first‑time builders who lack basic hand tools. You will need a 1/4‑in drill, a set of metric taps, and a torque wrench; without them the jig cannot be used effectively. Additionally, the kit is unsuitable for shooters seeking a fully finished lower that requires no machining.
What's in the box?
The box contains one RL556V3 polymer lower receiver blank, one full‑size RL556V3 jig kit, a set of eight M4‑size screws, a tap set for the trigger group, and a printed build guide. All components are pre‑spotted for rapid alignment, and the guide includes step‑by‑step photos to keep build time under 30 minutes.
Is the Polymer80 RL556V3 worth it at $99.99?
At $99.99, the kit delivers strong value for DIY AR‑15 enthusiasts. Compared to a CNC‑machined lower that can cost $180–$220, you save $80–$120 while retaining comparable durability. The only trade‑off is the required manual effort, but for builders who enjoy the process, the price‑to‑performance ratio is excellent.
For more AR‑15 lower options, see the .308 80% Lower – Billet or read our Complete FAQ on the 80% Lower Registration Process.
Specs at a glance
Pros & cons
What works
- Weighs 14.2 oz – 12% lighter than the LR‑308 kit
- Complete jig reduces build time to under 30 minutes
- Pre‑spotted holes improve alignment accuracy by 15%
Trade-offs
- Requires basic hand tools (drill, taps, torque wrench)
- No stippling or surface finish – additional finishing may add $30–$60
- Polymer may flex slightly under extreme stress compared to billet lowers
Key attributes
| Caliber | 5.56 NATO |
| Lower Type | 80% AR-15 |
| Weight | 14.2 oz (403 g) |
| Dimensions | 7.5 in x 2.5 in x 1.5 in (190 mm x 64 mm x 38 mm) |
| Material | High‑impact polymer |
| Condition | New |
| Included Components | Lower receiver blank, RL556V3 jig kit, screws, taps, build guide |
Frequently asked questions
- Is it compatible with standard AR-15 buffer tubes?
- Yes, the RL556V3 lower fits all standard AR‑15 buffer tubes. The internal dimensions are 1.5 in (38 mm) deep, matching the 14.5 in (368 mm) overall receiver length.
- Does it fit a Magpul PMAG 30-round magazine?
- It does. The magazine well is milled to a 0.896‑in (22.8 mm) width, which accommodates the Magpul PMAG 30‑round without modification.
- How long does shipping take?
- Standard US shipping is 3–5 business days; expedited options deliver in 1–2 days. All packages include tracking and are discreetly labeled.
- Can I return it if it doesn't fit?
- Yes, returns are accepted within 30 days of receipt if the lower is unused and in original packaging. A restocking fee of 15% applies to cover handling.
- Does this work with the ADI SafeFire trigger kit?
- It does. The trigger pocket is drilled to ADI's standard 0.563‑in (14.3 mm) spacing, allowing a direct install of the SafeFire kit.