Sig offers the MCX-R is 5.56NATO and 7.62X39 calibers that are optic ready and shooters also have the option to purchase the 5.56NATO with a ROMEO2 optic already installed. Sporting an Aluminum Frame finished in Gen 2 NiR FDE Cerakote the MCX-R is fitted with a Magpul SGA Stock and fully ambidextrous controls including the Mag Release Safety Selector and Bolt Catch. Additional features include the 16 inch Cold Hammer Forged Carbon Steel Barrel a 2 Stage Match Trigger and a 2-ported compensating muzzle brake on the 5.56 models and a 3-ported compensating muzzle brake on the 7.62X39 model. Engineered with a lower receiver that is compatible with all MCX Uppers every SIG MCX-R Regulator also includes a Receiver Integrated ARCA Rail.