Polymer80 RL556V3 – Rhino 80% AR15 Lower Receiver with Jig

If you are looking to build a custom AR-15 from the ground up, the polymer80 rl556v3 – rhino 80% ar15 lower receiver with jig is a solid starting point. This kit gives you the freedom to mill out your own lower at home, with the included jig taking the guesswork out of the process. We have seen a lot of 80% lowers come through our doors, and this one stands out for its thoughtful design and straightforward machining requirements. Whether you are a first-time builder or a seasoned hobbyist, this lower offers a practical way to complete a firearm on your own terms.

Overview

The Polymer80 RL556V3 Rhino is an unfinished 80% AR15 lower receiver that comes complete with a custom jig, drill bits, and end mill. Unlike many stripped lowers that require a dedicated workshop setup, this kit is engineered to work with a standard hand drill and a router (or drill press) to finish the fire control cavity and trigger pin holes. The receiver itself is molded from a reinforced polymer blend that matches the dimensions of a mil-spec aluminum lower, so you can drop in any standard AR15 upper and parts kit without modification. The included jig is reusable, which makes it a cost-effective choice if you plan to build multiple receivers later.

Features & Specs

• Reinforced polymer construction with integral trigger guard and flared magazine well for easier reloads
• Compatible with all mil-spec AR15 upper receivers, buffer tubes, and lower parts kits
• Includes a CNC-machined aluminum jig, two drill bits, and a 1/4-inch end mill – everything you need except the tool to drive them
• Accepts standard AR15 magazines (including PMAGs) and uses a standard bolt catch and rear takedown pin
• Hardware kit included with bolt catch, takedown pins, and trigger guard pin

The jig itself is the standout feature on this polymer80 rl556v3 – rhino 80% ar15 lower receiver with jig. It indexes directly off the receiver’s external surfaces, so you do not have to measure or mark anything. Just clamp it in place, follow the included instructions, and you will end up with a fully functional lower that is ready for assembly.

Who It’s For

This lower is ideal for the home builder who wants a hands-on project without investing in expensive tooling. If you are comfortable using a hand drill and a router (or a drill press), you can finish this receiver in an afternoon. It is also a great choice for those who prefer a lightweight build: the polymer frame shaves a few ounces off a standard aluminum lower, which can make a difference on a long day at the range. Because the polymer80 rl556v3 – rhino 80% ar15 lower receiver with jig uses standard AR15 components, you can customize the trigger, grip, and stock to your liking. Just keep in mind that you will need to follow all applicable federal, state, and local laws regarding the completion and serialization of 80% receivers.

Shipping & FFL

Since this is an unfinished 80% lower receiver, it is not considered a firearm by the ATF and can be shipped directly to your home address. No FFL transfer is required for the purchase or shipment of this item. However, once you complete the machining and assemble it into a functional firearm, you are responsible for complying with all laws in your jurisdiction, including any serialization requirements if you live in a state that mandates them. By purchasing the polymer80 rl556v3 – rhino 80% ar15 lower receiver with jig, you acknowledge that it is your responsibility to know and follow the law.