Dark Storm Industries DS15 AR-15 Stripped Billet Upper Receiver Mil-Spec Hard Coat Anodize Olive Drab Green Cerakote. 223 Remington .300 AAC Blackout Gun Make: AR Platform Gun Model: AR-15 Features of Dark Storm Industries DS-15 AR-15 Stripped Billet Upper Receiver Additional Rear Picatinny Rail Slot (14 vs 13) to Allow for Rearward Placement of Sights Enhanced Rear Angle Above Charging Handle to Reduce Possibility of Sling or Other Items Catching on Upper Aerospace Precision CNC Billet Fabrication (Tighter Tolerances Than Mil-Spec) MIL-PRF-46010H Everlube 9002 Internal Dry Film Lubricant Package Contents: Dark Storm Industries DS-15 AR-15 Stripped Billet Upper Receiver What firearm models does the manufacturer say Dark Storm Industries DS-15 AR-15 Stripped Billet Upper Receiver is compatible with? The manufacturer says that Dark Storm Industries DS-15 AR-15 Stripped Billet Upper Receiver is compatible with AR-15Dark Storm Industries DSI-URS-BL5-ODG: DS15 AR-15 Stripped Billet Upper Receiver Mil-Spec Hard Coat Anodize Olive Drab Green Cerakote