Shop › KNS AR/MCX STOCK ADAPTER WITH FLANGE KNS AR/MCX STOCK ADAPTER WITH FLANGE $51.00 KNS Precision, Inc. Stock Adapter with Flange, Fits AR-15, Converts Buffer Tube to 1913 Rail, Matte Finish, Black AR-MCX Adapter with Flange Quantity: Add To Cart Added! KNS Precision, Inc. Stock Adapter with Flange, Fits AR-15, Converts Buffer Tube to 1913 Rail, Matte Finish, Black AR-MCX Adapter with Flange