The classic AR-15 series of automatic weapons retains a considerable footprint the world over. Many manufacturers have adopted the rifle series in varying guises but the internal workings of this sound weapon system remain. This is the case with the relatively new SIG-Sauer MCX series automatic weapons, carrying over the traditional short-stroke, gas-operated piston action (with rotating bolt). As with other modern SIG offerings, the MCX is billed as a highly modular weapons system, capable of being reconfigured in a variety of ways to suit customer requirements. The series was introduced in 2015.
This sort of broad tactical value means that the MCX can also be made to chamber several cartridge types based on the configuration. The typical chambering is 5.56x45mm NATO but other forms chamber the 7.62x39mm Soviet as well as the .300 ACC Blackout round (7.62x35mm). All forms fire from a 30-round detachable box (STANAG type) magazine inserted ahead of the trigger group. The action is available in both semi- and selective-fire, again, to suit operator requirements (and also market restrictions).
Outwardly, the MCX takes on the conventional AR-15 style shape. The shoulder stock is hinged to fold over the receiver and is made to telescope while also absorbing a good amount of recoil. Over the top of the receiver is a long-running section of Picatinny rail for installing iron sights or specialized optics and aimers. The forend is heavily perforated for effective air cooling of the barrel. All controls are seated near the trigger area for ease of reach (including an ambidextrous manual safety). The barrel protrudes a short distance ahead of the forend and sports a three-pronged flash hider as standard. The barrel is user-changeable to fit the cartridge in play.
Overall weight of the system is in the 2.6 to 2.7 kilogram range and length, with the stock completely extended, is 35.7 inches. The barrel measures 16" in the standard carbine form.
The MCX SBR is the "short-barreled rifle" model (hence its designation) and this variant uses a 9" barrel. The MCX Pistol w/ SBX is a semi-automatic pistol model with a 9" barrel - essentially a very-compact-carbine. The MCX Low Visibility Assault Weapon (LVAW) is a suppressed model with a short barrel - reserved for purchase by military and police service only.
The MCX-MR was a "mid-range" offering at one point in contention for the United States Army's Compact Semi-Automatic Sniper System program (won by Heckler and Koch). It was chambered for 7.62x51mm NATO. With its 16" barrel, it would have seen service in the Designated Marksman (DM) role.
The newer MCX VIRTUS line includes the "Patrol", "Pistol" and "SBR" forms.
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April 2022 - The MCX-SPEAR has been selected by the U.S. Army for further development as the XM5 to succeed its aging line of M4A1 assault carbines through the Next Generation Squad Weapons Program. Similarly, the LMG-6.8 in the SIG lineup will become the XM250, succeeding the M249 SAW.
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(OPERATORS list includes past, present, and future operators when applicable)
✓Automatic Function
Features a mechanical function to automate the firing action.
✓Accuracy / Precision
Long-range accuracy / precision capable; suitable for sniping, particularly when equipped with sighting aids.
✓Special Forces
Qualities of this weapon have shown its value to Special Forces elements requiring a versatile, reliable solution for the rigors of special assignments.
Semi-Automatic
One shot per trigger pull; self-loading or auto-loading action aided by internal mechanism; trigger management (and initial cocking) typically required by the operator; subsequent shots are aided by the unlocked / moved bolt.
Rotating Bolt
System utilizes internal mechanism to lock the breech or rear barrel assembly prior to firing.
Gas-Operated
Gas-operated system is featured, typically involving a gas cylinder and rear-driven piston directing energy to the bolt component.
(Material presented above is for historical and entertainment value and should not be construed as usable for hardware restoration, maintenance, or general operation - always consult official manufacturer sources for such information)
*May not represent an exhuastive list; calibers are model-specific dependent, always consult official manufacturer sources. **Graphics not to actual size; not all cartridges may be represented visually; graphics intended for general reference only.
Max Eff.Range
1,650 ft (503 m | 550 yd)
Rate-of-Fire
800 rds/min
Muzzle Velocity
3,000 ft/sec (914 m/sec)
MCX - Base Series Designation
MCX Carbine - Base Carbine Model; 16" barrel length; civilian and police market trigger groups available.
MCX SBR ("Short-Barreled Rifle") - 9" barrel length; variable trigger group options.
MCX Pistol w/ SBX - Semi-automatic machine pistol form; 9" barrel length.
MCX LVAW ("Low Visibility Assault Weapon") - Select-fire action with short-barrel assembly and suppression assembly; military and police market model.
MCX-MR ("Mid Range") - Designated Marksman Rifle (DMR) form chambered for 7.62x51mm NATO; 16" fluted stainless steel barrel assembly; 8.9lb weight; M16-style cocking handle.
MCX VIRTUS - 5.56mm NATO or 300 Blk chambering; 16" barrel length; semi-automatic action.
MCX VIRTUS Patrol - 5.56mm NATO or 300 Blk chambering; 16" barrel length; semi-automatic action.
MCX VIRTUS Pistol - Very compact carbine variant; SBX pistol stabilizing brace.
MCX VIRTUS SBR - Short-barreled rifle form.
MCX-SPEAR - Available chamberings include 7.62 NATO, 6.5 Creedmoor, and 277 SIG FURY; over-receiver Picatinny; two-stage match trigger; adjustable folding stock.
MCX-SPEAR LT - Features of the Gen 1 MCX with MCX Virtus; 5.56 NATO, .300 Blackout, 7.62x39mm chamberings available; marketed in carbine, SBR, and pistol forms with varying barrel lengths.
XM5 - US. Army developmental designation of MCX 6.8 SPEAR.
XM250 - U.S. Army developmental designation of LMG-6.8.
XM250
Ribbon graphics not necessarily indicative of actual historical campaign ribbons. Ribbons are clickable to their respective campaigns / operations.
Images Gallery
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Image from official SIG-Sauer marketing material.
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