This is a WMD Guns Pistol known as the NiB-X AR-15 Pistol chambered in 223 Remington, model NIBXARPISTOL-RSR.
To build an AR platform unlike any other" WMD Guns coated every exterior surface with NiB-X" an exclusive nickel boron formulation. So you get a finish that's 40% harder than chrome" and incredibly resistant to moisture" corrosion" and wear. Key internal components are coated with NiB-X to reduce friction & wear" for an action that's incomparably smooth" utterly reliable" and as close to self-cleaning as you can get.
Features:
Pistol buffer
Optics ready
Nickel boron coated
Free float rail
Low profile gas block