San Tan Tactical STT-15 AR-15 Lower – 5.56x45 / .223 Rem, Semi-Automatic, Black

The San Tan Tactical STT-15 lower receiver is built for shooters assembling or upgrading AR-15 platform rifles chambered in .223 Rem / 5.56x45 NATO. Designed as a semi-automatic lower, the STT-15 serves as the core foundation for custom builds—whether you’re putting together a lightweight range gun, a duty-ready carbine, or a reliable training rifle.

Finished in black, this lower accepts standard AR-15 parts and is compatible with a wide array of aftermarket components including stocks, triggers, and controls. Please confirm whether the listing is for a stripped lower or a complete lower with parts kit, and verify material and manufacturing details (for example forged vs. billet aluminum) so shoppers have full confidence at checkout.

Ideal for gunsmiths, OEM builders, and DIY enthusiasts, the San Tan Tactical STT-15 offers a flexible platform for building a dependable 5.56/.223 rifle.