| SIG MCX | |
|---|---|
|   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 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) | 
 
  Australia: MCX Rattler Used by the NSW Police Force Tactical Operations Unit  [40]  and Victoria Police Special Operations Group in .300 AAC Blackout. [41]  [42]  .300 AAC Blackout variants have been acquired for Army special forces units since 2024 to replace the H&K MP5. [43]  [44]
  Australia: MCX Rattler Used by the NSW Police Force Tactical Operations Unit  [40]  and Victoria Police Special Operations Group in .300 AAC Blackout. [41]  [42]  .300 AAC Blackout variants have been acquired for Army special forces units since 2024 to replace the H&K MP5. [43]  [44]  Belgium: DSU  [45]  and the special response unit of the Ghent local police (COPS). [46]
  Belgium: DSU  [45]  and the special response unit of the Ghent local police (COPS). [46]  Canada: Saskatchewan Conservation Officers, [47]  Canadian Special Operations Forces Command
  Canada: Saskatchewan Conservation Officers, [47]  Canadian Special Operations Forces Command  Denmark: Jægerkorpset, [48]  Rigspolitiet phasing in until 2027. [49]
 Denmark: Jægerkorpset, [48]  Rigspolitiet phasing in until 2027. [49]  Estonia: Used by the K-Commando. [50]
  Estonia: Used by the K-Commando. [50]  France: Groupement de commandos de montagne, 27th Mountain Infantry Brigade, 5 in 2021. [51]
  France: Groupement de commandos de montagne, 27th Mountain Infantry Brigade, 5 in 2021. [51]  Germany: Berlin Police, 300 modified MCXs to meet the police's requirements were ordered in October 2017, [52]  plus an additional 160 units for the SEK of Berlin, [53]  Landespolizei of Schleswig Holstein, 531 units delivered, but being replaced with HK 437 because the rifles had shortcomings [54]  Rhineland-Palatinate Police: more than 100 rifles ordered in late 2019. [55]
  Germany: Berlin Police, 300 modified MCXs to meet the police's requirements were ordered in October 2017, [52]  plus an additional 160 units for the SEK of Berlin, [53]  Landespolizei of Schleswig Holstein, 531 units delivered, but being replaced with HK 437 because the rifles had shortcomings [54]  Rhineland-Palatinate Police: more than 100 rifles ordered in late 2019. [55]  Israel: Used by Shayetet 13, the Israel Defense Forces Naval Commando unit. [56]
  Israel: Used by Shayetet 13, the Israel Defense Forces Naval Commando unit. [56]  Italy: Used by Comando Raggruppamento Subacquei e Incursori Teseo Tesei (Frogmen) of the Italian Navy. [57]
 Italy: Used by Comando Raggruppamento Subacquei e Incursori Teseo Tesei (Frogmen) of the Italian Navy. [57]  Indonesia: Used by Kopassus (Special Forces Command) of the Indonesian Army in limited service; Detachment 88 and Mobile Brigade Corps of the Indonesian National Police; [58]  [59]  [60]  [61]  Also used by Kopasgat (Quick Reaction Forces Command) of the Indonesian Air Force; [62]  [63]  and Koopssus (Special Operations Command) of the Indonesian National Armed Forces. [64]  [65]
  Indonesia: Used by Kopassus (Special Forces Command) of the Indonesian Army in limited service; Detachment 88 and Mobile Brigade Corps of the Indonesian National Police; [58]  [59]  [60]  [61]  Also used by Kopasgat (Quick Reaction Forces Command) of the Indonesian Air Force; [62]  [63]  and Koopssus (Special Operations Command) of the Indonesian National Armed Forces. [64]  [65]  Netherlands: Used by the Netherlands Maritime Special Operations Forces and the Dienst Speciale Interventies. The rifles are chambered for .300 AAC Blackout and fitted with the SIG Suppressed Upper Receiver. [66]  [67]
  Netherlands: Used by the Netherlands Maritime Special Operations Forces and the Dienst Speciale Interventies. The rifles are chambered for .300 AAC Blackout and fitted with the SIG Suppressed Upper Receiver. [66]  [67]  Poland:  Jednostka Wojskowa Grom  and  JW Formoza  acquired the SIG MCX VIRTUS and MCX RATTLER in .300 AAC Blackout with conversion kits to 5.56×45mm NATO and 7.62×39mm ammunition. [68]  Also used by Internal Security Agency  [69]  and State Protection Service. [70]
  Poland:  Jednostka Wojskowa Grom  and  JW Formoza  acquired the SIG MCX VIRTUS and MCX RATTLER in .300 AAC Blackout with conversion kits to 5.56×45mm NATO and 7.62×39mm ammunition. [68]  Also used by Internal Security Agency  [69]  and State Protection Service. [70]  Portugal: Polícia de Segurança Pública acquired SIG MCX in 5.56×45mm NATO. Used by Special Operations Group (Portugal). [71]
  Portugal: Polícia de Segurança Pública acquired SIG MCX in 5.56×45mm NATO. Used by Special Operations Group (Portugal). [71]  Switzerland: Used by the Geneva Police. [72]
  Switzerland: Used by the Geneva Police. [72]  Spain: Used by Spanish Navy  [73]  and Civil Guard. [74]
 Spain: Used by Spanish Navy  [73]  and Civil Guard. [74]  Ukraine: Used by the SBU Alpha Group. [75]
  Ukraine: Used by the SBU Alpha Group. [75]  Sweden: Used by Swedish Military Intelligence and Security Service National Intelligence Unit. [76]
 Sweden: Used by Swedish Military Intelligence and Security Service National Intelligence Unit. [76]  United Kingdom: Used by the Police Counter Terrorist Specialist Firearms Officers including the Metropolitan Police Service  [77]  and United Kingdom Special Forces to replace the HK MP5SD3s. [78]  Adopted as the L143A2 by United Kingdom Commando Force Littoral Response Group (LRG). [79]  In March 2025, 1,500 rifles were ordered for the Royal Marines. [80]  [81]  A contract document for indoor shooting ranges which briefly refers to the L143A2 indicates that the weapon is used with both 5.56x45mm and .300 AAC Blackout ammunition in British military service. [82]
  United Kingdom: Used by the Police Counter Terrorist Specialist Firearms Officers including the Metropolitan Police Service  [77]  and United Kingdom Special Forces to replace the HK MP5SD3s. [78]  Adopted as the L143A2 by United Kingdom Commando Force Littoral Response Group (LRG). [79]  In March 2025, 1,500 rifles were ordered for the Royal Marines. [80]  [81]  A contract document for indoor shooting ranges which briefly refers to the L143A2 indicates that the weapon is used with both 5.56x45mm and .300 AAC Blackout ammunition in British military service. [82]  United States: various models including the RSAR (Reduced Signature Assault Rifle), LVAW (Low Visibility Assault Weapon) and the CSAW (Close Support Assault Weapon) are used by Joint Special Operations Command. [83]
  United States: various models including the RSAR (Reduced Signature Assault Rifle), LVAW (Low Visibility Assault Weapon) and the CSAW (Close Support Assault Weapon) are used by Joint Special Operations Command. [83]  Quotations related to  SIG MCX  at Wikiquote
  Quotations related to  SIG MCX  at Wikiquote