Premium Fire/Safe Marked Billet 80% Lower Assembly
SKU: P80-BILLET-FS | Price: $148.49
Not just a part. It’s the foundation of a rifle built your way.
Stop Fighting Your Build. Start Finishing It.
You know the drill. You get an 80% lower, the parts kit, and then the real “fun” begins: chasing that damn rear takedown pin detent across the garage, swearing at the bolt catch roll pin. We built this Premium Billet Lower to fix that. This isn’t a rehashed forging; it’s a purpose-machined billet receiver designed by builders who’ve been there. We added threaded holes where you need them most, turning the most frustrating steps of your AR-15 build into a simple, screwdriver job. Get back to what matters—crafting a reliable, accurate rifle.
What Makes This Lower Different:
- Threaded Bolt Catch Pin Hole: No more roll pins or hammers. The bolt catch installs with a provided screw and hex key. It’s secure, aligned, and takes 30 seconds.
- Threaded Rear Takedown Detent Hole: Say goodbye to the “spring launch.” Your detent and spring are captured with a small screw. This single feature saves time, temper, and spare parts.
- FIRE/SAFE Selector Markings: Professionally engraved, clean, and permanent. It gives your build a finished, factory look right out of the gate.
- Material: 7075-T6 Aluminum Billet: We start with a solid block of aerospace-grade aluminum, not a forging. This gives us stronger, more consistent walls and a noticeably more rigid feel. This is a lower meant for hard use.
- Broached Mil-Spec Magwell: Magazines insert and drop free cleanly, every time. The interior is machined to mil-spec dimensions for guaranteed compatibility.
What You Get in the Box:
This is a complete lower assembly kit. You won’t need to hunt down extra parts.
- One (1) Billet 80% Lower Receiver: Anodized Mil-Spec Black, Fire/Safe engraved.
- Complete Lower Parts Kit (LPK): All springs, detents, trigger, hammer, disconnector, selector, mag catch, and pivot/takedown pins to complete your lower.
- Buttstock & Buffer Tube Assembly: A carbine-length buffer tube, buffer, spring, castle nut, end plate, and a standard 6-position stock. Everything to get your receiver extension ready.
- Installation Screws & Hex Key: The specific hardware needed to use the threaded bolt catch and rear detent features.
Note: You will need a jig, drill press (or router), and basic machining tools to complete the fire control group pocket and drill the trigger and selector holes. This is an 80% lower receiver, as defined by federal law.
Specifications & Details
- Material: 7075-T6 Aluminum (Billet)
- Finish: Type III Hardcoat Anodized, Mil-Spec Black
- Markings: FIRE / SAFE Selector Engravings
- Compatibility: Mil-Spec AR-15 platform
- Origin: 100% Machined and Finished in the USA
- Legal Status: This is a firearm component. It is NOT a firearm. NO FFL IS REQUIRED for purchase or shipment to most states. It is the buyer’s responsibility to know and comply with all federal, state, and local laws regarding the purchase, completion, and possession of 80% receivers.
Built Here, Built Right
At Polymer80Buy, we sell parts we’d use ourselves. This Premium Billet Lower is the result of direct feedback from the builder community. The threaded fixes aren’t gimmicks; they’re solutions to real problems. Starting with a billet block means we control every dimension for a tighter fit with your upper receiver. The 7075-T6 aluminum ensures it will stand up to the stress of thousands of rounds. When you combine that with the included, quality parts kit and stock assembly, you’re getting a true foundation for a duty-grade rifle. This is for the builder who values their time and demands performance from every component.
Ready to build it right? Add the Premium Billet Lower Assembly to your cart. Check your local laws, gather your tools, and let’s get building.
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