Stern Defense Mag-AD9 9mm/40 S&W AR-15 Magazine Adapter - Sig P320/P250 & S&W M&P Compatible

The Stern Defense Mag-AD9 is a drop-in AR-15 magazine well adapter that converts any standard mil-spec AR-15, M4, or M16 lower to accept 9mm and 40 S&W pistol-caliber magazines. This is the M&P / P320 variant, engineered to feed from Smith & Wesson M&P 9mm/40 magazines as well as Sig Sauer P320 and P250 pistol magazines.

The adapter is CNC machined from aircraft grade aluminum and finished in a rugged Type 3 hard anodized black coating. It installs in seconds with no permanent modifications to the host lower. For proper function, the host firearm requires a 9mm or 40 S&W barrel matched to the chambering of the magazines being used. The Mag-AD9 works with all generations of M&P magazines and accepts the full line of Sig P320 and P250 magazines.

A practical choice for a dedicated pistol-caliber carbine build, a law enforcement training rifle, or any shooter who wants to share standard pistol magazines between a handgun and an AR-platform pistol-caliber carbine.