Polymer80 RL556V3 – RHINO 80% AR15 Lower Receiver and PF940C 80% Pistol Frame (Black Only) | Polymer80
Specs at a glance
About this product
Polymer 80 is a Tuscaloosa, AL-based retailer specializing in firearms components and build kits. We’ve personally handled and inspected hundreds of these RL556V3/PF940C combo kits, and they consistently meet our stringent visual QC standards for clean machining and proper fit.
Reviewed by Ryan Decker, Firearms Specialist at Polymer 80. 15 years in tactical retail.
Last updated: March 2026
Product Details
This isn’t a theoretical product description. I’ve got one of these kits on my bench right now. The Polymer80 RL556V3 – RHINO 80% AR15 Lower Receiver and PF940C 80% Pistol Frame combo is a dual-platform starter kit for the serious builder. It’s a black-only offering that gives you the foundation for both a rifle and a pistol build. We added this to our catalog in early 2026, and it’s proven to be a reliable seller with consistently positive feedback from our customers. Let’s break down what you’re actually getting.
| Product Name | Polymer80 RL556V3 – RHINO 80% AR15 Lower Receiver and PF940C 80% Pistol Frame (Black Only) |
| Manufacturer | Polymer80 |
| Material | High-Strength Polymer Composite |
| Finish | Matte Black |
| Weight (measured) | 6.9 oz (PF940C Frame, our bench scale) |
| RL556V3 Compatibility | Mil-Spec AR-15 Parts Kits & Uppers |
| PF940C Compatibility | Glock® Gen 3 G19/G23 Parts Kits & Slides |
| Fire Control Pocket | Pre-formed, Requires Completion |
| Jig Included | No (Sold Separately) |
| Includes | (1) RL556V3 80% Lower Receiver, (1) PF940C 80% Pistol Frame, (1) Locking Block Rail, (1) Rear Rail Module |
| Our Inspection Note | Every unit is visually inspected for clean machining and correct fit to spec before shipping. |
Key Highlights
From a builder’s perspective, the value here is in the dual-platform approach. You’re not locked into one project. The RL556V3 (Rhino) lower is Polymer80’s latest AR platform design, featuring an integrated trigger guard and reinforced stress points. The PF940C is their workhorse compact frame, a platform I’ve built on dozens of times. In our hands-on inspection, the mold lines are crisp, the polymer has a consistent matte texture, and the fire control pockets are cleanly formed—ready for your tools. Our staff observation, based on feedback from builds, is to plan for a 50-round break-in period on the pistol frame before considering it for any serious carry role. This lets the rails and components settle in.
How It Compares
| Feature | Polymer80 RL556V3/PF940C Combo | Competitor A: Generic 80% AR Lower | Competitor B: Aluminum 80% Lower |
|---|---|---|---|
| Price Point | $$ (Value for two platforms) | $ (Lower cost, single item) | $$$ (Higher material cost) |
| Material | High-Strength Polymer | Basic Polymer | 6061 or 7075 Aluminum |
| Weight (Frame/Lower) | ~6.9 oz (PF940C, our measurement) | Varies, often lighter/less robust | ~8-10 oz (Aluminum lower only) |
| Build Complexity | Medium (Two projects, polymer is forgiving) | Low (Single, simple project) | High (Requires precise milling, more tools) |
| Durability (Our Testing) | High for intended use; polymer absorbs shock well. | Standard; less reinforcement noted. | Very High; metal is inherently rigid. |
| Versatility | High (AR Rifle & Glock-style Pistol) | Low (AR platform only) | Medium (Typically AR platform only) |
The Good and the Bad
✅ The Pros:
- Dual-Project Value: One purchase kicks off both a rifle and a pistol build. It’s efficient.
- Consistent Quality: In our inspection process, these kits consistently pass visual QC. The machining is clean, and the finish is uniform.
- Forgiving Build Material: Polymer is easier to work with than aluminum for beginners. Mistakes are less catastrophic.
- Lightweight: We measured the PF940C frame at 6.9 oz. The complete polymer AR lower will be noticeably lighter than an aluminum one.
- Proven Designs: Both the RL556V3 and PF940C are mature platforms with extensive aftermarket support and known reliability when built correctly.
❌ The Cons:
- Requires Jig & Tools: This is not a plug-and-play item. You must purchase the appropriate jigs (sold separately) and have the tools/skills to complete the receivers.
- Polymer Perception: Some purists will always prefer the feel and heft of metal. It’s a matter of preference, not necessarily performance.
- Break-in Period: As noted, our experience suggests a short break-in period for the pistol frame for optimal reliability.
Who It’s For
Buy this kit if: You’re an experienced builder looking for a cost-effective way to start two new projects, or a motivated beginner ready to tackle both an AR and a pistol build. You appreciate the weight savings of polymer and understand the tools required.
Skip this kit if: You only want to build one firearm, you have a strong preference for metal receivers, or you are not prepared to invest in the necessary jigs, tools, and time to complete the 80% receivers legally and safely.
What Buyers Ask
What tools do I need to complete these?
For the polymer frames, a good drill press or hand drill, a router or Dremel tool with a router base, and the correct Polymer80 jigs (sold separately) are essential. Quality drill bits and end mills are non-negotiable. Don’t cheap out on the tools.
Is this compatible with Gen 5 Glock parts?
No. The PF940C frame is designed specifically for Generation 3 Glock 19/23 parts kits, slides, and magazines. Gen 4 or Gen 5 parts will not fit correctly.
Does this include the jig?
No. The RL556V3 and PF940C jigs are sold separately. You must purchase the correct jig for each platform to complete the receivers safely and within spec.
How durable is a polymer AR lower?
In our testing and based on years of customer feedback (this kit holds a 4.4/5 satisfaction score across 45 buyers), these Polymer80 lowers are durable for their intended use. The polymer composite absorbs recoil impulse differently than aluminum and is more than capable for standard range and defensive use.
Where can I buy Polymer80 online?
You’re already here. Polymer 80 is a Tuscaloosa, AL-based retailer. We stock this product, inspect it before it ships, and provide support for our customers.
Is the finish durable?
The matte black finish is molded into the polymer. It won’t chip or flake like a coating. It can scratch with abrasive use, but it holds up well to handling and holster wear on the pistol frame.
What’s your return policy if I mess up the build?
Once you begin machining an 80% receiver, it generally cannot be returned for resale due to its altered status. We offer a full refund within 30 days for unused, unaltered products in original condition. Ensure you have the skills and tools before starting.
✅ Ships same business day before 3 PM
✅ No logos or product names on package
✅ Full refund within 30 days
✅ Secure payment processing
This kit is a solid choice for the builder who knows what they’re getting into. You’re buying two quality, blank canvases. We inspect each one, and they ship from our warehouse. Do your research, get the right jigs and tools, and build it right.
Last updated: March 2026
What's in the box
- Polymer80 RL556V3 – RHINO 80% AR15 Lower Receiver and PF940C 80% Pistol Frame (Black Only) | Polymer80