The SIG MCX-R Regulator is the newest member of Sig's MCX family. Equipped with an Aluminum frame, it is finished in Gen2 NiR FDE Cerakote. Additional features include a 16 inch, cold hammer forged carbon steel barrel, a Magpul SGA Stock and fully ambidextrous Mag Release, Safety Selector and Bolt Catch. Sig offers this new MCX-R Regulator Rifle in 5.56NATO. A SIG designed 2-port Compensating Muzzle Brake on the 5.56 models is accompanied by a Receiver Integrated ARCA Rail, with a lower receiver that is compatible with all MCX Uppers.