The Stern Defense 001SDMAGADMP9AND40/P32 Mag-AD9 9mm/40 S&W Adapter is a drop-in magazine well conversion that lets a standard mil-spec AR-15, M4, or M16 lower run Smith & Wesson M&P and Sig P320/P250 pistol magazines. Machined from black 6061-T6 aircraft-grade aluminum with a Type III hard coat anodized finish and integrated steel feed ramp, it delivers a solid, precise interface between your lower receiver and pistol mags while preserving the familiar AR controls.

This adapter is ideal for shooters who want their pistol-caliber carbine to share magazines with their duty or carry pistol, simplifying logistics for training days and range sessions. It installs in seconds with no permanent modifications, provides true last-round bolt hold open, and works with any mil-spec 5.56 lower when paired with the appropriate 9mm or .40 S&W barrel and Glock-cut bolt. Stern Defense’s attention to machining quality and thoughtful engineering has made the Mag-AD9 a respected option among enthusiasts seeking a reliable AR-9 conversion.

Key Features:

• Manufacturer: Stern Defense
• Model: Mag-AD9 001SDMAGADMP9AND40/P32
• Caliber: 9mm / .40 S&W
• Condition: New
• Gun Model Compatibility: AR-15, M4, M16 mil-spec lowers
• Magazine Compatibility: S&W M&P, Sig P320, Sig P250 magazines
• Material: 6061-T6 aircraft-grade aluminum with 4140 NiB-coated feed ramp
• Finish Color: Black Type III hard coat anodized
• Unique Features: Last-round bolt hold open, ergonomic mag release, drop-in installation, requires Glock-cut bolt
• Length: 8.65 inches
• Dimensions: 3.45 x 4.40 x 8.65 inches