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 the foundational piece you need. This kit bridges the gap between raw material and a functional, serialized lower, giving you hands-on control over your build without requiring a full machine shop. We have worked with these kits on our own benches and know exactly what they offer the home gunsmith.

Overview

The Polymer80 80% Lower Receiver and Jig Kit (LR-308) is designed for the builder who wants a polymer lower for the DPMS-pattern LR-308 platform. The kit includes the 80% lower receiver itself, plus the essential jig and tooling needed to complete the fire control pocket and trigger pin holes. Because it is an 80% receiver, it is not considered a firearm by the ATF and can be shipped directly to your door. You complete the machining at home, then add your own upper, barrel, and parts kit. This specific kit from Polymer80 is built around their proven polymer formulation, which offers a solid balance of weight savings and durability for a large-frame build.

Features & Specs

• Manufacturer: Polymer80 — a trusted name in the 80% receiver market known for their precision jig systems and durable polymer construction.
• Category: Build Kits — includes the lower receiver, jig, drill bits, end mill, and instructions. You supply the patience and a power drill.
• Compatible with LR-308 (DPMS pattern) uppers and parts kits — not for AR-10 (Armalite pattern) components, so verify your upper before starting.

The jig system in this Polymer80 80% Lower Receiver and Jig Kit (LR-308) is a key selling point. It guides your drill bit and end mill with steel bushings, reducing the risk of wandering holes. The polymer lower itself features a reinforced buffer tube tower and an integrated trigger guard, saving you one more part to source. The kit does not include a rear takedown pin detent or spring, so you will want to have your lower parts kit ready before you start drilling.

Who It’s For

This kit is aimed at the intermediate to advanced builder who is comfortable using a drill press or handheld drill and has some experience with metal or polymer finishing. It is not a beginner’s first project unless you are willing to take your time and follow the instructions carefully. The Polymer80 80% Lower Receiver and Jig Kit (LR-308) is ideal for someone who wants to build a lightweight, large-frame rifle for hunting or long-range target shooting without paying a premium for a fully assembled lower. Because you are completing the receiver yourself, you also get the satisfaction of saying “I built that” when you take it to the range.

Shipping & FFL

Because this is an 80% lower receiver, it is not a firearm and does not require transfer through a Federal Firearms License (FFL) holder. We ship the Polymer80 80% Lower Receiver and Jig Kit (LR-308) directly to your residential or business address. However, once you complete the machining, the receiver becomes a firearm under federal law. You must serialize it per your state and local regulations before assembling it into a functional rifle. Some states and municipalities have specific laws regarding 80% receivers, including serialization requirements or outright bans. It is your responsibility to know and comply with all applicable laws in your jurisdiction before purchasing or completing this kit. We strongly recommend checking your local statutes before placing your order.

• No FFL required for purchase or shipment of the uncompleted receiver.
• You must be 18 years or older to purchase this kit (21 in some states for handgun frames; this is a rifle receiver).
• Once machined, the completed lower must be serialized and used only in compliance with federal, state, and local law.