SIG MCX | |
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![]() SIG MCX with a skeleton folding stock | |
Type | Assault rifle Carbine Semi-automatic rifle |
Place of origin | United States [1] |
Service history | |
In service | 2015–present |
Production history | |
Designed | 2013 |
Manufacturer | SIG Sauer |
Unit cost | MCX VIRTUS Patrol: MSRP US$2,233 MCX VIRTUS SBR: MSRP US$2,233 MCX VIRTUS Pistol: MSRP US$2,235 [2] |
Produced | 2015–present |
Variants | See Variants |
Specifications | |
Mass | 2.61 kg (5.8 lb) (229 mm barrel) 2.72 kg (6.0 lb) (292 mm barrel) 3.6 kg (7.9 lb) (406 mm barrel) |
Length | 730 mm (29 in) stock unfolded (229 mm barrel) 908 mm (35.7 in) stock unfolded (406 mm barrel) |
Barrel length | 229 mm (9.0 in) 292 mm (11.5 in) [3] 406 mm (16.0 in) |
Cartridge | 5.56×45mm NATO .300 AAC Blackout 7.62×39mm |
Action | Gas-operated short-stroke piston, rotating bolt |
Rate of fire | 800–900 rounds/min |
Muzzle velocity | MCX Carbine 5.56×45mm NATO: 3,000 ft/s (914 m/s) [4] |
Effective firing range | MCX Carbine 5.56×45mm NATO: 1,650 ft (503 m) [4] |
Feed system | 30-round detachable STANAG box magazine |
Sights | Picatinny rail for mounting iron or optical sights |
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 latter configuration generally conforming to the definition of a compact carbine but for taking a pistol brace rather than a buttstock). [5]
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.
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. [1]
In 2016, SIG recalled some of the rifles that had the first-generation bolt carrier group. [6]
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. [7]
The SIG MCX series features a short-stroke gas piston [8] with dual recoil spring system to reduce recoil and improve the reliability of the weapon; [9] this was based on the design of the earlier SIG MPX. [10] 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. [10] The MCX is designed to deliver optimal performance with .300 AAC Blackout and an optional suppressor. [11]
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. [12] [13] It features hardened steel wear points. [10] [12]
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 are available for the MCX carbine. [10] [13] The overall layout of the two rifles is similar. [14] SIG designed the upper receiver to be compatible with standard AR-15 and M16 lower receivers [10] [12] with the help of an adapter. [15]
An integrally suppressed upper receiver group based on the MCX was selected by USSOCOM for the SURG (Suppressed Upper Receiver Group) contract in July 2018. These suppressed uppers would be paired with existing M4A1 lowers in SOCOM inventory. [16] [17]
The SIG MCX family has undergone three generations of modifications.
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. [10]
SIG Sauer offers the MCX in semi-automatic only in three different configurations for the civilian market:
The SIGMCX Low Visibility Assault Weapon (LVAW) is a short-barreled, suppressed, select-fire variant available only to military and law enforcement agencies. It is nicknamed the "Black Mamba". [21] [22]
The SIG MCX VIRTUS is the second generation of the SIG MCX series and was introduced in 2017.
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". [26]
The defining features of the MCX-SPEAR LT are a lightened handguard and barrel design (borrowed from the MCX-SPEAR), 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 (black options are still available for purchase).
The MCX-SPEAR LT is available in 5.56×45mm NATO, .300 Blackout and 7.62×39mm calibers. The civilian model features 11.5-inch (290 mm) or 16-inch (410 mm) 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 14.5-inch (370 mm) and 9-inch (230 mm) barrels, as well as a custom two-stage match grade select-fire trigger group. [27] [28]
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 140 mm (5.5 in) barrel, and comes with a Picatinny rail tail interface for attaching either a compact buttstock or a folding PCB (pistol contour brace). [29] In February 2018, USSOCOM ordered upper receiver group conversion kits for the MCX Rattler in .300BLK for evaluation. [30]
The MCX Rattler was later selected as the winner of SOCOM's Commercial Personal Defense Weapon (CPDW) contract in May 2022 and suppressed MCX Rattlers will be ordered in 5.56 and .300BLK. [31]
The SIG MCX Rattler LT is a variant that incorporates the design features of the MCX-SPEAR LT. [32]
The SIG MCX-MR (Mid Range), chambered in 7.62×51mm NATO cartridge, was SIG Sauer's unsuccessful submission for the United States Army's Compact Semi-Automatic Sniper System (CSASS) program. [33] 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 8.9 lb (4.0 kg) and a 406 mm (16.0 in) 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. [34]
The SIG MCX-SPEAR was developed as SIG Sauer's submission for the United States Army Next Generation Squad Weapon (NGSW) program and is chambered in 6.8×51mm SIG Fury cartridge. [35] [36] [37] [38] 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. [39]
![]() | This section possibly contains original research .(August 2025) |