The SIG MCX is a series of self-loading rifles[disambiguation needed] designed and manufactured by SIG Sauer, featuring a short-stroke gas piston system, carried over from the SIG MPX submachine gun. The rifle is produced in both selective fire and semi-automatic configurations. It is available in rifle, short-barreled rifle, and pistol (generally considered as a compact carbine) configurations.<br /><br />The SIG MCX was first introduced at SHOT Show 2015.<br /><br />In 2016, SIG recalled some of the rifles that had the first generation bolt carrier group.<br /><br />The SIG MCX series features a short-stroke gas piston system to reduce recoil and improve the reliability of the weapon; this was based on the design of the earlier SIG MPX. The MCX features a system that allows for conversion between 5.56×45mm NATO, .300 AAC Blackout, and 7.62×39mm ammunition, using standard 5.56 mm STANAG magazines for 5.56×45mm NATO and .300 AAC Blackout, and specially designed STANAG-compatible magazines for 7.62×39mm.The MCX is designed to deliver optimal performance with .300 AAC Blackout and an optional suppressor.<br /><br />The barrel's profile is tapered at the crown to allow the installation of muzzle devices and direct-thread sound suppressors without the use of washers that degrade performance and allows the devices to self-center on installation. The barrel can be changed in a matter of seconds to another length or a different caliber. Additionally the barrels are nitride coated for corrosion resistance. It features hardened steel wear points.<br /><br />All MCX variants have a forend made of aluminum with a KeyMod system to add accessories. Controls are mostly ambidextrous including the charging handle but not the bolt release. Four types of stocks are available for the MCX carbine.<br /><br />SIG designed the upper receiver to be compatible with standard AR-15 and M16 lower receivers with the help of an adapter. The overall layout of the two rifles is similar.
