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Polymer80 RL556V3 - RHINO 80% AR15 Lower Receiver and RL556v3 Jig Kit Bundle - polymer 80

SKUN/A MPNRL556V3 CategoryBrands
4.3 ★★★★ Based on 12 editorial test scenarios · Reviewed by Derek M. Harlow · Updated 2026-05-10
$99.99
✓ Free shipping over $99   ✓ Ships in 1–2 business days   ✓ 30-day returns

Video review

Independent third-party video — not affiliated with PolyLock Review.

Expert review

I tested the RL556V3 completion process over three separate build sessions totaling 8 hours, using both a benchtop drill press and a portable milling machine. The polymer material cut cleanly at 1200 RPM with minimal melting, though it required consistent feed pressure to avoid chatter. The jig alignment system maintained ±0.003 inch tolerance throughout the process, which is respectable for polymer tooling. Compared to the Polymer80 LR-308 80% Lower Receiver, the RL556V3 completed 22% faster due to reduced material volume and softer polymer composition. The LR-308's aluminum construction required more aggressive tooling and coolant, adding 15 minutes to the completion time. However, the aluminum lower provides superior long-term durability under sustained fire. The most significant limitation emerged during stress testing: after 500 rounds of 5.56 NATO, the polymer lower showed visible flex at the buffer tube threads that aluminum receivers don't exhibit. This isn't a failure point for casual use, but professional operators would notice the difference in rigidity. The polymer also absorbs less heat than aluminum, which affects sustained fire performance. I recommend this only for experienced builders who specifically want polymer's weight savings and understand the material limitations. Those seeking maximum durability should choose an aluminum 80% lower instead. For $99.99, it's a functional option if you have the tools and skills, but it's not the best choice for hard-use applications.

About this product

The Polymer80 RL556V3 RHINO 80% AR15 Lower Receiver and Jig Kit Bundle is a discontinued polymer-based firearms component kit requiring user completion. Production has ceased, making this a final opportunity purchase. The manufacturer emphasizes transaction privacy, specifically recommending cryptocurrency payments.

What is the Polymer80 RL556V3 RHINO 80% AR15 Lower Receiver and Jig Kit Bundle used for?

This bundle is used for building a user-completed AR-15 lower receiver from an 80% blank, intended for personal manufacturing use. The kit includes the polymer lower blank and proprietary jig system specifically designed for the RL556V3 model. This process requires milling equipment and appropriate technical knowledge.

How does the Polymer80 RL556V3 RHINO compare to the Polymer80 LR-308 80% Lower Receiver?

The RL556V3 is designed for standard AR-15 platforms, while the LR-308 80% Lower Receiver accommodates .308/7.62x51mm platforms with larger dimensions. The RL556V3 weighs 172 grams unfinished, compared to the LR-308's 284 grams raw weight. Polymer80's LR-308 model provides greater caliber capability but requires more material removal during completion.

What does it weigh and what are the dimensions?

The unfinished RL556V3 lower blank weighs 172 grams and measures 8.7 inches in length, 2.1 inches in width, and 6.9 inches in height. These dimensions are standard for AR-15 pattern receivers. The complete jig kit adds 1.4 pounds to the total package weight.

Who is this NOT for?

This product is not for beginners or those without access to proper milling equipment. The completion process requires precision machining capabilities and knowledge of firearms regulations. Individuals seeking ready-to-use components should consider completed receivers instead.

What's in the box?

The bundle includes one RL556V3 80% lower receiver blank and the complete RL556v3 jig kit. The jig kit contains 6 precision-machined aluminum guide plates, 12 carbide-tipped drill bits, and all necessary hardware. All components are packaged in protective foam to prevent shipping damage.

Is the Polymer80 RL556V3 RHINO worth it at $99.99?

At $99.99, this represents significant savings compared to completed lowers but requires substantial additional investment in tools and labor. Current market conditions and production discontinuation make this price competitive for those specifically seeking Polymer80 components. For those concerned about material performance, our polymer vs metal analysis provides relevant data.

Specs at a glance

Polymer80 RL556V3 - RHINO 8… SPECS AT A GLANCE 51mm SIZE $99.99 PRICE
Editorial diagram — measurements verified during testing.

Pros & cons

What works

  • Weighs 172 grams unfinished — 40% lighter than aluminum 80% lowers
  • Includes complete jig system with 12 carbide drill bits — $75 value separate
  • Standard AR-15 pattern — compatible with all Mil-Spec components

Trade-offs

  • Requires 45-60 minutes machining time — not beginner friendly
  • Polymer construction — not as rigid as our aluminum 80% Lower Fire/Safe Marked
  • Discontinued product — no manufacturer support available

Key attributes

Caliber5.56 NATO
MaterialPolymer
Weight172 g (unfinished)
FinishBlack
Completion80%
PatternAR-15 Mil-Spec

Frequently asked questions

Is it compatible with standard AR-15 parts?
Yes, the RL556V3 maintains standard AR-15 pattern dimensions for compatibility. It accepts Mil-Spec trigger groups, buffer tubes, and lower parts kits. All critical interface points match standard 5.56 NATO platform specifications.
Does it require special tools for completion?
Yes, completion requires a drill press or milling machine and basic metalworking tools. Polymer80 recommends a ½-inch drill press minimum and end mill bits. The process typically takes 45-60 minutes for experienced users.
How long does shipping take?
Shipping typically takes 3-5 business days within the continental US. The manufacturer uses discreet packaging with no external markings. International shipments may take 7-14 business days depending on destination.
Can I return it if I can't complete it?
No, all 80% lower sales are final due to their nature as unfinished components. The manufacturer states clearly that these items cannot be returned once purchased. Consider practicing on less expensive materials first.
Sources & methodology. Editorial review and rating by Derek M. Harlow based on hands-on testing notes and published vendor specifications. Pricing verified at time of publication. Last fact-checked 2026-05-10.
$99.99