Stern Defense SD-BU45 .45 ACP 8620 Steel Mag Phosphate AR-15/M16 Bolt

The Stern Defense SD-BU45 is a dedicated .45 ACP bolt engineered for AR-15/M16 platform builds chambered in pistol caliber. Machined from 8620 AISI steel and finished in Mag Phosphate for durability and corrosion resistance, this bolt is designed to drop into compatible uppers feeding from Glock-pattern .45 ACP magazines.

The SD-BU45 is built to fit Mil-Spec and Glock-pattern upper receivers, making it a direct replacement or build component for AR-15 pistol caliber carbines and rifles running .45 ACP. Whether you are assembling a dedicated .45 ACP PCC upper or completing a caliber conversion on an existing AR-15 platform, this bolt delivers the locking and cycling interface needed for reliable function.

As part of Stern Defense's BU45 line, this bolt carries the same construction standards used across the company's AR-15 pistol-caliber offerings, pairing a robust steel body with the proven Mag Phosphate coating recognized throughout the firearms industry.