SIG MCX


The SIG MCX is a family of firearms designed and manufactured by SIG Sauer, produced in both selective fire and semi-automatic only models, and features a short-stroke gas piston system, which is inherited from the earlier SIG MPX submachine gun. The MCX is available in rifle, carbine, short-barreled rifle, and pistol configurations.
The MCX was further developed into the SIG MCX Spear, which was adopted in its .277 Fury chambering as the XM7 rifle by the U.S. Army in 2022.

History

The SIG MCX was introduced at SHOT Show 2015. The rifle was originally designed by SIG USA, the subsidiary of SIG Sauer based in New Hampshire.
In 2016, SIG recalled some of the rifles that had the first-generation bolt carrier group.
The MCX has been used by various SWAT teams and militaries, including the Ukrainian Armed Forces during the Russian Invasion of Ukraine.
An MCX was used in the 2016 Orlando nightclub shooting, which was the deadliest mass shooting in U.S. history, until exceeded by the 2017 Las Vegas shooting.

Design details

The SIG MCX series features a short-stroke gas piston with dual recoil spring 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 enables 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.
The barrel's profile is tapered at the crown to enable the installation of muzzle devices and direct-thread sound suppressors without the use of washers that degrade performance and enables 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.
First generation MCX variants have a forend made of aluminum with a KeyMod system to add accessories while second generation MCX variants have an M-LOK handguard. Controls are mostly ambidextrous including the charging handle but not the bolt release. Sig produces four stock configurations for the MCX carbine. The overall layout of the two rifles is similar. SIG designed the upper receiver to be compatible with standard AR-15 and M16 lower receivers with the help of an adapter.
An integrally suppressed upper receiver group based on the MCX was selected by USSOCOM for the SURG contract in July 2018. These suppressed uppers would be paired with existing M4A1 lowers in SOCOM inventory.

Variants

The SIG MCX family has undergone three generations of modifications.

SIG MCX (Gen I)

The SIG MCX is available with a safe/semi-automatic trigger group for the U.S. civilian market, or safe/semi-automatic/fully automatic trigger group for the military and law enforcement agencies.
SIG Sauer offers the MCX in semi-automatic only in three different configurations for the civilian market:
  • The SIG MCX PATROL is the standard configuration of the rifle with a 406 mm barrel.
  • The SIG MCX SBR is a short-barreled rifle configuration of the rifle with a 229 mm barrel.
  • The SIG MCX Pistol is the pistol configuration of the rifle with a 229 mm barrel or 292 mm barrel and comes either with the SIG Sauer SBX or SIG Sauer PCB. though it is really a compact carbine rifle, as it fires an intermediate round.
The SIG 'MCX Low Visibility Assault Weapon ' is a short-barreled, suppressed, select-fire variant available only to military and law enforcement agencies. It is nicknamed the "Black Mamba".

SIG MCX VIRTUS (Gen II)

The SIG MCX VIRTUS is the second generation of the SIG MCX series and was introduced in 2017.
  • The SIG MCX VIRTUS Patrol is the standard configuration rifle that features a 406 mm barrel, a 1:7 inch twist, a custom SIG Matchlite Duo Trigger for improved accuracy, a folding and collapsing 5-position stock, four handguard lengths to choose from, interchangeable barrels and a special internal recoil system.
  • The SIG MCX VIRTUS SBR is the short-barreled rifle configuration of the MCX VIRTUS. It features a 292 mm barrel for the 5.56×45mm NATO caliber, and a 140 mm barrel and 229 mm barrel for the.300 AAC Blackout caliber.
  • The SIG MCX VIRTUS Pistol is the pistol configuration of the MCX VIRTUS which features an SBX stabilizer brace. It features an 292 mm barrel for the 5.56×45mm NATO caliber, and a 229 mm barrel for the.300 AAC Blackout caliber.

SIG MCX-SPEAR LT (Gen III)

The SIG MCX-SPEAR LT is the third generation of the SIG MCX, introduced in 2022. With the release of the MCX-SPEAR LT, SIG also designed a new, padded, side-folding stock with an FDE finish option to match the rifles, which civilian versions of the rifle variant are sold with. While the civilian version is referred to as the "MCX-SPEAR LT", referencing the SPEAR from which it derives many of its improvements over the MCX Virtus line, SIG Sauer refers to the military versions as simply the "MCX LT" or "MCX Lightweight".
The defining features of the MCX-SPEAR LT are a lightened handguard and barrel design, an ambidextrous bolt catch and release, a proprietary SL muzzle device to allow for the use of SIG SAUER's quick detaching SLX and SLH suppressors, a custom 28-round AR-pattern magazines when chambered in 7.62×39mm cartridge, and a coyote brown coating.
The MCX-SPEAR LT is available in 5.56×45mm NATO, .300 Blackout and 7.62×39mm calibers. The civilian model features or barrel and a Picatinny rail tail interface for attaching either a buttstock or a pistol brace. The military model features both of these options, with the addition of and barrels, as well as a custom two-stage match grade select-fire trigger group.

SIG MCX RATTLER

The SIG MCX RATTLER is a short-barreled rifle variant chambered in .300 AAC Blackout and 5.56. It is intended to serve as a personal defense weapon, featuring a barrel, and comes with a Picatinny rail tail interface for attaching either a compact buttstock or a folding PCB. In February 2018, USSOCOM ordered upper receiver group conversion kits for the MCX Rattler in.300BLK for evaluation.
The MCX Rattler was later selected as the winner of SOCOM's Commercial Personal Defense Weapon contract in May 2022 and suppressed MCX Rattlers will be ordered in 5.56 and.300BLK.
The SIG MCX Rattler LT is a variant that incorporates the design features of the MCX-SPEAR LT.

Derivatives

SIG MCX-MR

The SIG MCX-MR, chambered in 7.62×51mm NATO cartridge, was SIG Sauer's unsuccessful submission for the United States Army's Compact Semi-Automatic Sniper System program. The MCX-MR features both an M16/AR-15 type charging handle and a left side charging handle, a selective fire trigger mechanism, and uses a 20-round SR-25 box magazines. It has an empty weight of and a fluted, 416 stainless steel barrel with a 1:10 inch twist, which is manufactured by Bartlein Barrels. The gas system features suppressed and unsuppressed settings. Unlike the handguard of the MCX, which slides off after pulling the front pivot pin, the MCX-MR requires popping off two screws first.

SIG MCX-SPEAR

The SIG MCX-SPEAR was developed as SIG Sauer's submission for the United States Army Next Generation Squad Weapon program and is chambered in 6.8×51mm SIG Fury cartridge. SIG Sauer was chosen as the winner on 19 April 2022, formerly designated as the XM5, then was later changed to the XM7 and was later typed classified as the M7 in the U.S. military service.

Users