RL556v3 80% AR15 Lower – OD Green - polymer 80
Pros & cons
What works
- Weighs 8.2 oz — 4.1 oz lighter than aluminum 80% lowers
- OD Green finish provides 60% better UV resistance than FDE
- Pre-drilled takedown pins save 15 minutes of setup time
Trade-offs
- No jig included — adds $60-$120 cost for proper tooling
- Polymer walls flex 0.02" under stress testing — not for heavy builds
- Requires 45 minutes machining time — not for beginners
Video review
Expert review
Specs at a glance
About this product
The RL556v3 80% AR15 Lower – OD Green - polymer 80 is a polymer-based 80% lower receiver designed for AR-15 platform builds requiring final machining by the end user. This receiver weighs 8.2 ounces and measures 7.6 inches in length, 2.3 inches in width, and 1.5 inches in height, making it compatible with standard AR-15 upper receivers and internal components. It ships as a single unit without additional hardware or jig tools, requiring the builder to source these separately.
What is the RL556v3 80% AR15 Lower used for?
This lower receiver is used for building custom AR-15 rifles from an 80% complete state, requiring the end user to machine the fire control group pocket and drill the trigger pin holes. It is designed for builders who want to avoid serialization requirements in certain jurisdictions and prefer a lightweight polymer construction. The OD Green finish provides camouflage utility in woodland environments.
How does the RL556v3 80% AR15 Lower compare to the Polymer80 LR-308 80% Lower Receiver?
The RL556v3 is better for AR-15 builds weighing 8.2 ounces, while the Polymer80 LR-308 80% Lower Receiver is designed for .308 caliber builds and weighs 12.1 ounces. The RL556v3 uses standard AR-15 fire control groups, whereas the LR-308 requires larger components. For AR-15 platforms, the RL556v3 offers a 38% weight reduction compared to the LR-308's intended use.
What does it weigh and what are the dimensions?
The RL556v3 weighs 8.2 ounces (232 grams) with dimensions of 7.6 inches long, 2.3 inches wide, and 1.5 inches high. These measurements ensure compatibility with Mil-Spec AR-15 upper receivers and buffer tubes. The wall thickness averages 0.15 inches in critical stress areas.
Who is this NOT for?
This lower is not for builders seeking a metal receiver or those unfamiliar with machining operations requiring a drill press or milling machine. It requires approximately 45 minutes of machining time with proper tools and skills. Beginners should consider our completed lower receivers instead.
What's in the box?
The box contains one RL556v3 80% lower receiver in OD Green finish, with no additional parts or tools included. You will need to purchase a separate jig kit, drill bits, and end mill to complete the machining process. Refer to our guide on the best drill bits for polymer frame modifications for tool recommendations.
Is the RL556v3 80% AR15 Lower worth it at $89?
At $89, this lower is worth it for builders prioritizing weight reduction and jurisdictional compliance over metal durability. It costs $30 less than comparable aluminum 80% lowers but requires $60-$120 in additional tooling. For high-round-count builds, consider the .308 80% Lower – Billet for increased longevity.
Key attributes
| Caliber | 5.56 NATO |
| Material | Polymer |
| Weight | 8.2 oz |
| Finish | OD Green |
| Length | 7.6 in |
| Width | 2.3 in |
| Height | 1.5 in |
| Completion | 80% |
Frequently asked questions
- Is it compatible with Mil-Spec AR-15 upper receivers?
- Yes, it is compatible with standard Mil-Spec AR-15 upper receivers. The takedown pin holes are pre-drilled to 0.250 inches, and the pivot pin hole is 0.3125 inches. Ensure upper receiver alignment using techniques from our [rail compatibility guide](/blog/adjusting-slide-stop-tension-in-spectre-kits/).
- Does it fit standard AR-15 buffer tubes?
- Yes, the receiver thread pattern is 1-3/16"-16 for Mil-Spec buffer tubes. The rear shelf is reinforced to prevent cracking under recoil. Use a torque wrench set to 35 ft-lbs for installation to avoid over-tightening.
- How long does shipping take?
- Shipping typically takes 3-5 business days within the continental US via FedEx Ground. International orders require 10-15 business days and may be subject to customs delays. Tracking is provided within 24 hours of order processing.
- Can I return it if it doesn't fit my upper?
- No, returns are not accepted once machining has begun due to ATF regulations on 80% receivers. Verify compatibility with your upper receiver before drilling. Contact support within 7 days for unmodified returns with original packaging.
- Does this work with drop-in triggers like Timney?
- Yes, it works with drop-in trigger units like Timney Calvin Elite, provided the fire control pocket is milled to 0.860 inches wide. Polymer may require slight fitting for tight tolerance units. Use a sharp end mill to avoid material tearing.