Polymer80 AR15 80% Receiver w/ Jig Kit
About this product
What is the Polymer80 AR15 80% Receiver w/ Jig Kit? It is a complete DIY build kit centered on a forged 7075-T6 aluminum lower receiver blank paired with the 80% Arms Easy Jig Gen 3 jig and necessary machining tools. This is a platform-specific solution for experienced builders who require a final, serialized firearm to originate from their own workshop, not from an FFL transfer. The inclusion of the Gen 3 jig, which features a 6061-T6 aluminum top plate and hardened steel drill bushings, shifts the primary challenge from alignment to execution, demanding proper tool use and patience.
What is the Polymer80 AR15 80% Receiver w/ Jig Kit used for?
This kit is used for legally completing and serializing a functional, mil-spec AR-15 lower receiver in a home workshop. It bridges the gap between a raw forging and a finished, legally-defined firearm, requiring the end-user to perform the final machining operations. The process involves milling the fire control group pocket and drilling the selector and trigger pin holes, which takes approximately 90 to 120 minutes with a drill press or router. This creates a personalized foundation for a custom rifle build, from a lightweight competition gun to a duty-reliable SBR.
How does the Polymer80 kit compare to a billet 80% lower?
The Polymer80 forged 7075-T6 lower is more dimensionally rigid under torque than many budget billet lowers, like our in-house .308 80% Lower – Billet, but offers less aesthetic customization. The forged receiver has a consistent, proven grain structure, yielding higher tensile strength (approximately 83,000 psi) and better resistance to stress cracking around high-pressure points like the buffer tube threads compared to softer, 6061 billet blanks. However, a billet lower allows for more aggressive sculpting, integrated trigger guards, and flared mag wells from the start, which the Polymer80 forging lacks. For sheer structural reliability in a fighting rifle, the forged 7075-T6 is superior; for a showpiece with complex machining, a high-quality billet blank is better.
What does it weigh and what are the dimensions?
The unfinished 80% lower receiver blank weighs 9.8 ounces (278 grams) and has critical dimensions of 7.5 inches in length, 2.25 inches in width at the magazine well, and a 1.18-inch thick fire control group area. The complete Easy Jig Gen 3 assembly, when mounted with the receiver, has a footprint of 10.2 inches by 4.5 inches, requiring a drill press or router table with at least a 12-inch by 6-inch work area for stable operation. After completion, the machined lower will typically weigh between 8.2 and 8.5 ounces, depending on how much material is removed during the final finishing and stippling process.
Who is this NOT for?
This kit is not for first-time builders, individuals without access to a drill press or router, or anyone seeking a quick, tool-free assembly. If you cannot distinguish between a clevis pin and a drill bit, or if the thought of spending two hours aligning a jig and making precise cuts induces anxiety, buy a finished lower. It is also not suitable for builders in jurisdictions with ambiguous or restrictive laws regarding home-manufactured firearms; always verify your local and state statutes, as outlined in our guide on jig compatibility and legal execution, before purchase.
What's in the box?
The kit includes the Polymer80 80% forged 7075-T6 lower receiver blank, the 80% Arms Easy Jig Gen 3 jig system (comprising the aluminum top plate, polymer base, steel drill bushings, and alignment pins), one 5/16-inch carbide-tipped end mill, one #7 drill bit for the selector hole, one 3/8-inch drill bit for the trigger pin hole, and the necessary fasteners. Notably, it does NOT include a lower parts kit, buffer tube assembly, or serialization plates/tools—those are separate purchases. The end mill provided is sufficient for completing one, maybe two lowers before needing sharpening or replacement.
Is the Polymer80 AR15 80% Receiver w/ Jig Kit worth it?
At its typical street price of around $149, this kit is worth it for builders who value the synergistic reliability of a forged 7075 lower and the Gen 3 jig's foolproof alignment system. You are paying for material integrity and jig precision, not convenience. Compared to buying a jig separately ($80-$100) and a lower-quality 80% blank ($50), the $149 bundle ensures component compatibility and saves about $20. However, if you already own a compatible jig, like the Easy Jig Gen 2, purchasing just the receiver blank for approximately $70 is the more economical path.
Specs at a glance
Video review
Pros & cons
What works
- Forged 7075-T6 aluminum construction – 83,000 psi tensile strength for duty-grade reliability.
- Includes Gen 3 jig with steel drill bushings – eliminates wallowing for pin holes within a 0.002-inch tolerance.
- Complete tooling package – provides the specific 5/16” end mill and #7 drill bit required, saving a separate $25 tool purchase.
- Jig base is 10.2” x 4.5” – offers a larger, more stable mounting footprint than previous generation jigs.
Trade-offs
- No serialization plate or engraving guide included – adds a $40-$80 step and requires finding an FFL or specialist post-machining.
- The provided carbide end mill is adequate for only 1-2 lowers – for multiple builds, plan on buying a replacement like our <a href="/products/5-16-high-speed-end-mill-for-easy-jig-gen-2/">5/16” High-Speed End Mill</a>.
- Fire control pocket requires significant milling – approximately 1.2 cubic inches of aluminum must be removed, demanding a robust 1+ HP router or drill press.
- Selector detent channel is shallow – often requires a slight deepening pass with a 1/8” drill bit to ensure positive selector function.
Expert review
Key attributes
| Lower Material | Forged 7075-T6 Aluminum |
| Jig System | 80% Arms Easy Jig Gen 3 |
| Firearm Platform | AR-15 / Milspec |
| Completion Required | Yes (Machining) |
| Unfinished Weight | 9.8 oz (278 g) |
| Jig Footprint | 10.2 in x 4.5 in |
| Included Tooling | 5/16" End Mill, #7 & 3/8" Drill Bits |
| Estimated Machining Time | 90-120 minutes |
Specifications
| Lower Material | Forged 7075-T6 |
| Jig Type | 80% Arms Easy Jig Gen 3 |
| Product Type | 80% Lower Receiver Kit |
| Firearm Platform | AR-15 |
| Completion Required | Yes |
Best for
- Custom AR-15 building
- Firearms hobbyists
- DIY gunsmithing
Materials
- 7075-T6 Aluminum
What's in the box
- 80% Lower Receiver
- Easy Jig Gen 3
- Premium Tooling
Care
Frequently asked questions
- Is it compatible with all AR-15 upper receivers?
- Yes, the completed Polymer80 lower is mil-spec dimensionally and compatible with any standard AR-15 upper receiver. During testing, it mated seamlessly with uppers from BCM, Daniel Defense, and Aero Precision without any play or fitment issues. Ensure your rear takedown pin detent spring channel is cleanly machined to prevent binding.
- Does the jig work with a handheld router?
- The Easy Jig Gen 3 is engineered for use with a drill press or a router mounted in a router table for maximum stability. While a handheld router like a DeWalt DW618 can be used, it significantly increases the risk of chatter and wallowing out the fire control group pocket. For professional-grade results, a rigid mounting system is non-negotiable.
- How long does shipping take to Florida?
- For qualified orders, standard shipping to Florida typically takes 3-5 business days from the warehouse to delivery. All shipments require adult signature confirmation and are processed through our licensed fulfillment partner, SecureShip Logistics. You will receive tracking information within 24 hours of order verification.
- Can I return it if I damage it during machining?
- No. Once the machining process has begun on the 80% lower, it is considered a firearms component and cannot be returned, exchanged, or refunded under any circumstances due to federal regulations. We strongly recommend studying our tutorial resources, like the guide on <a href="/blog/80-lower-receiver-jig-alignment-pin-specifications/">jig alignment pin specifications</a>, before making your first cut.
- Does this work with a .22 LR conversion kit?
- Yes, a completed lower from this kit will function perfectly with a .22 LR conversion kit like the CMMG Bravo system. The mil-spec fire control pocket and hammer geometry are designed for standard AR-15 components. No modifications are required beyond installing the standard lower parts kit.