The FMK Firearms AR-1 (brand part no. FMKGAR1ETB) is a stripped AR-15 lower receiver chambered in .223 Remington/5.56 NATO and manufactured in the USA from a high-impact proprietary composite polymer rather than aluminum, finished in blue. FMK markets the AR-1 as the strongest composite polymer lower on the market, delivering superior strength and unmatched durability while staying extremely lightweight. It’s a lightweight alternative for builders who want to shed weight without moving to a billet aluminum receiver, with a distinctive blue finish that stands out from standard black.

Key Specifications

• Molded from a high-impact composite polymer rather than aluminum.
• Chambered in .223 Remington/5.56 NATO, the standard AR-15 chambering pair.
• Runs a semi-automatic action, standard for AR-15-pattern builds.
• Finished in blue, a distinctive option apart from standard black.
• Sold as a stripped receiver, giving full control over trigger and safety selection.
• Manufactured in the USA and backed by a lifetime warranty.
• Weighs approximately 4.3 ounces, dramatically lighter than a standard aluminum lower.
• Mil-spec compatible, accepting any standard mil-spec AR-15 upper receiver.
• Rated for calibers from .22 LR up to .50 Beowulf with a compatible upper.

Frequently Asked Questions

Is this receiver made from aluminum? No, it’s molded from a high-impact composite polymer rather than aluminum.

Does it include a trigger or buffer tube? No, this is a stripped lower receiver sold without internals.

Buy the FMK AR-1 Polymer AR-15 Lower Receiver, Blue

Shed weight without sacrificing durability, part of our AR15 lowers selection. Order it from our Lubbock, Texas gun shop for fast, insured shipping to your FFL.