Stern Defense SD BU9 9mm Luger Bolt Mag Phosphate 8620 Steel AR-15/M16

The Stern Defense SD BU9 is a complete 9mm Luger bolt assembly engineered for the AR-15/M16 platform. Machined from 8620 AISI steel and protected by a Mag Phosphate finish, this complete bolt delivers dependable cycling for dedicated 9mm AR builds and pistol-caliber conversions.

The SD BU9 incorporates a custom 4140 billet extractor for superior cartridge extraction and a Glock-cut magazine interface, making it directly compatible with both Colt SMG and Glock-pattern 9mm magazines. It is designed to function with standard AR-15/M16 charging handles and installs into both Mil-Spec and Glock-pattern upper receivers, giving builders a versatile component for completing or refreshing a 9mm AR upper.

Crafted to Stern Defense's standards for AR-15/M16 components, the SD BU9 brings rugged construction and reliable function to any 9mm blowback or dedicated pistol-caliber AR build.