The San Tan Tactical STT-15 is a billet AR-15 lower receiver machined from 7075-T6 aluminum. It has a Type III hard coat anodized finish with a matte black surface treatment. Tolerances are held to ±0.005″ on critical dimensions.

This lower features an integrated AR-Gold trigger pocket for drop-in compatibility with aftermarket triggers. The oversized magwell flare accommodates faster magazine changes. All fire control group pin holes are CNC-machined to mil-spec spacing.

The STT-15 accepts standard AR-15 upper receivers and standard lower parts kits. It is compatible with carbine or rifle buffer systems. The threaded bolt catch roll pin hole accepts #4-40 hardware.

This is a serialized firearm component. It must ship to an FFL holder for transfer. No magazine or other accessories are included with the bare receiver.

Jake Morrison’s shop notes

San Tan Tactical STT-15 billet lower receiver observed with 0.002” tighter magwell clearance compared to standard forged lowers. Trigger pin holes consistently measure 0.1545” diameter across inspected units. Requires slight chamfering on rear takedown pin hole for smoother detent engagement during assembly.

Tested: 1557 rounds bench-cycled. Pocket tolerance measured: within 0.0008″ on this batch. Weight (actual): 8.4 oz on shop scale. Units shipped from Phoenix in May 2026: 73.