Choosing an AR-15 80% Lower Receiver
Because an 80% lower isn’t yet a finished receiver, it gives you control over how your rifle comes together — caliber, parts, and finish are up to you. The two decisions that matter most when choosing one are the manufacturing method and whether you want a jig included.
Billet vs. forged
Forged lowers are made by pressing heated aluminum into shape, producing a strong, dimensionally consistent part at a lower cost — the standard choice for most builds. Billet lowers are CNC-machined from a solid block of aluminum, which allows more distinctive styling and integrated features but usually costs more. Both are made to mil-spec dimensions, so either works with standard AR-15 parts; the choice is mostly about budget and looks.
With or without a jig
Completing an 80% lower requires a jig to guide the drilling and milling. Many of our listings are 80% lower and jig combos that include the jig and hardware, which is the simpler route if you don’t already own one. If you have a reusable jig, a standalone lower keeps the cost down.
Features that vary by model
Some — not all — of our 80% lowers add features beyond the basics: flared magwells for faster reloads, integrated or enhanced trigger guards, and tensioning or reinforced details. Check each product page for its specific feature set, finish, and whether a jig is included. Color and Cerakote options vary by model as well.
Building it out
An 80% lower is one piece of the rifle. To finish a build you’ll pair it with a complete upper or stripped upper, a lower parts kit, and a stock or brace assembly. Browse our lower parts kits and complete uppers to match components to your project.
Frequently Asked Questions
What is an 80% lower receiver?
An 80% lower is a receiver that is roughly 80% machined and is not yet a functional firearm. The builder completes the remaining machining — the fire-control cavity, trigger slot, and pin holes — to finish it. It’s the starting point for building an AR-15 from parts.
What’s the difference between a billet and a forged 80% lower?
Forged lowers are pressed from heated aluminum — strong, consistent, and economical. Billet lowers are CNC-machined from solid aluminum, allowing more styling and integrated features at a higher price. Both use mil-spec dimensions and accept standard AR-15 parts.
Do I need a jig to finish an 80% lower?
Yes. A jig guides the drilling and milling needed to complete the receiver. Many of our listings include a jig in an 80% lower and jig combo; standalone lowers assume you already have one.
Do you need an FFL to buy an 80% lower receiver?
It depends on how the item is sold and where you live. Following the 2025 U.S. Supreme Court decision in Bondi v. VanDerStok, certain partially complete receivers — particularly those sold as kits with a jig and the parts needed to readily complete them — can be treated as firearms, which means they must be serialized and transferred through a licensed dealer. Individual unfinished lowers sold without a kit are often handled differently. Because the rules turn on these details and continue to evolve, confirm the current federal requirement and how a specific product ships before ordering.
Are 80% lowers legal in my state?
Federal law and state law are separate, and state law on unfinished receivers and self-built firearms varies widely — some states restrict or prohibit them outright, while others allow personal builds with little oversight. Check the current law in your own state before purchasing. This page is general information, not legal advice.
