Polymer80 80% Lower Receiver and Jig Kit (LR-308)

If you are looking to build your own large-frame AR platform from the ground up, the Polymer80 80% Lower Receiver and Jig Kit (LR-308) is a strong starting point. This kit gives you the core structure of a .308 lower receiver along with the essential tools to complete it at home. Whether you are a first-time builder or a seasoned hobbyist, this kit provides a straightforward path to a custom firearm without the need for a serialized receiver.

Overview

The Polymer80 80% Lower Receiver and Jig Kit (LR-308) is designed for builders who want hands-on control over their rifle. The kit includes an unfinished lower receiver made from impact-resistant polymer, plus a reusable jig system that guides your drilling and routing. This is not a drop-in part; it requires basic workshop skills and patience. But for those who enjoy the process, the result is a receiver that feels solid and fits standard LR-308 components. The jig is the standout feature here, as it simplifies the most critical machining steps and helps reduce the chance of errors.

Features & Specs

This kit is built around the Polymer80 LR-308 platform, which is compatible with most DPMS-pattern large-frame AR parts. The polymer lower is reinforced in high-stress areas to handle the recoil of .308 cartridges. The included jig is made from precision-machined aluminum and can be reused for multiple builds. Here are the key specs and features you need to know:

• Manufacturer: Polymer80. Category: Build Kits. Compatible with DPMS pattern LR-308 upper receivers and parts kits.
• Receiver material: high-impact polymer with glass-filled nylon reinforcement for durability and weight savings.
• Includes: one 80% lower receiver, one reusable aluminum jig, drill bits, end mill, and step-by-step instructions.

This kit does not include a fire control group, buffer tube, or stock. You will need to source those separately, along with an upper receiver assembly. The jig requires a drill press or a handheld drill with a steady hand. Take your time with the milling process, and the result will be a clean, functional lower receiver.

Who It Is For

This kit is ideal for the DIY builder who wants to learn the mechanics of the LR-308 platform. It is also a good choice for those who prefer to keep their build off the books, as the 80% receiver is not considered a firearm by the ATF until it is machined into a functional state. However, you must be legally allowed to own a firearm to complete this build. The Polymer80 80% Lower Receiver and Jig Kit (LR-308) is not for someone who wants a quick, plug-and-play solution. It requires mechanical aptitude, patience, and basic tool skills. If you enjoy tinkering and have a few hours to dedicate to the project, this kit will reward you with a receiver you built yourself.

• Best for experienced AR builders or motivated beginners who have studied the process.
• Not recommended for those who lack a drill press or steady hand tools.
• Requires a separate upper receiver, barrel, bolt carrier group, and lower parts kit to complete the rifle.

Shipping & FFL

Because the Polymer80 80% Lower Receiver and Jig Kit (LR-308) is an unfinished receiver, it is not classified as a firearm by the Bureau of Alcohol, Tobacco, Firearms and Explosives. This means it can be shipped directly to your doorstep with no FFL transfer required. However, once you complete the machining, you are responsible for ensuring compliance with all local, state, and federal laws. We recommend checking your state’s regulations before ordering, as some states restrict or prohibit 80% receivers. No background check is needed for this purchase, but you must be at least 18 years old and not a prohibited person. For any questions about shipping lead times or restrictions, contact our customer service team.

• No FFL transfer needed for the unfinished receiver. Ships directly to your door.
• You are solely responsible for complying with all applicable laws in your jurisdiction.
• We recommend consulting local regulations before completing your build.