Polymer80Outlet AR-9 80% Lower Receiver – Billet 9mm, Fire/Safe Marked

This isn’t just another lower. This is a dedicated 9mm billet lower built from the ground up for reliability and a clean, professional build. If you’re building an AR-9, starting with a purpose-built foundation is the only way to go.

We start with a solid block of 6061-T6 billet aluminum. Our CNC machines don’t just mill it out; they precision-cut every critical dimension to true mil-spec. The result is a lower with superior structural integrity and a perfect fit for your jig and parts kit. The Type III hardcoat anodizing isn’t for show—it’s the toughest finish we can apply, providing a matte black, wear-resistant surface that stands up to range time and handling.

Function is where this lower really separates itself. The mag well is flared and features enlarged ramps. This isn’t a minor tweak; it’s a major upgrade for faster, smoother reloads when it counts. It’s designed specifically for GLOCK® OEM and ETS magazines, the most common and reliable options in the AR-9 platform. The integrated trigger guard is robust and ready for any glove, and the fire/safe markings are deeply engraved for a permanent, professional look.

This is a serious component for a serious builder. You get the unmatched feel of billet aluminum, the durability of military-grade finishing, and the functional enhancements that actually matter. All of it is made right here in the USA.

For your build, you’ll need: a standard AR-15 lower parts kit, a 9mm-specific buffer system, and your preferred AR-9 upper receiver. This is an 80% lower receiver; completion requires machining with the appropriate tools, knowledge, and in compliance with all federal, state, and local laws.

Note: This is an unfinished firearm component (80% lower). Purchaser is responsible for completion in accordance with all applicable laws. Polymer80Outlet.com is not responsible for unauthorized use or modification. Check your state and local laws before purchasing.