Stern Defense Mag-AD9 Magazine Adapter Features The Stern Defense Mag-AD9 installs into any mil spec AR-15 M4 or M16 lower receiver converting it to accept Sig Sauer P320 and P250 pistol magazines in 9mm or .40 S&W. All of the rifle s other components aside from the bolt and barrel remain stock so the conversion does not require a dedicated pistol caliber lower. A 4140 NiB coated feed ramp smooths feeding from the pistol magazine into a 9mm or .40 caliber barrel while an ergonomic magazine release keeps manipulation intuitive for shooters already familiar with the AR platform. The adapter is engineered to work with all generations of M&P and P320/P250 magazines giving owners flexibility in magazine choice. Machined from 6061 T6 aircraft grade aluminum and finished in a hard coat type 3 anodized black finish the Mag-AD9 is built to handle the repeated cycling of a pistol caliber carbine without wearing prematurely. A last round bolt hold open feature replicates standard AR manual of arms letting the shooter know definitively when the magazine runs dry. The adapter requires use of a Glock cut bolt along with a 9mm or .40 S&W barrel and Stern Defense recommends a buffer of 5.4 ounces or heavier when paired with a carbine spring. Manufactured entirely in the USA the Mag-AD9 is a practical upgrade for anyone building a pistol caliber carbine around magazines they already carry. Stern Defense Mag-AD9 Magazine Adapter Specifications Manufacturer: Stern Defense Model: Mag-AD9 Type: Magazine Adapter Color: Black Material: Aircraft Grade Aluminum Finish: Hard Anodized Compatible Hosts: Sig Sauer P320 P250 Caliber: 9mm / .40 SW Available At: GrabAGun