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SIG-Sauer M5 (XM5)

Modular Assault Carbine [ 2025 ]

The SIG-Sauer MCX SPEAR was selected by the United States Army to succeed its aging line of M4 assault carbines.

Authored By: Staff Writer | Last Edited: 04/20/2022 | Content ©www.MilitaryFactory.com | The following text is exclusive to this site.

The MCX-SPEAR serves as the basis of the United States Army's chosen successor to the storied and long-running M4A1 SOPMOD assault carbine line. The MCX family was debuted by SIG in 2015 and includes a complete line-up of related products for even the most discerning AR-15 user. At the core of the design is its inherent modularity which has made it a popular firearm in a market overflowing with solid options. The MCX-SPEAR was an announced expansion of the MCX family tree in January of 2022.

While the SIG MCX-MR (Mid-Range) failed in its bid to cover the Army's "Compact Semi-Automatic Sniper System" (CSASS) program, the MCX-SPEAR was awarded further development (as the "XM5") ahead of others as part of the service's "Next Generation Squad Weapons" (NGSW) program established in 2017/2018. The program seeks to replace the aging stock of Army M4 carbines, M249 SAW machine guns, and M240 Medium Machine Guns (MMGs) and their associated cartridge types to provide a new-generation of warfighters new tools to deal with emerging global threats.

The MCX-SPEAR is a further evolution of the AR-15 and features all-modern qualities including ambidextrous fire controls, a long section of Picatinny rail over the frame / forend, a vented forend, two-stage match trigger, and adjustable / folding shoulder stock (six positions). Internally, the gun uses a short stroke gas piston (2-position adjustable) with rotating bolt and is billed as a multi-caliber automatic weapon, firing the 7.62x51mm NATO, 6.5 Creedmoor, and 277 SIG FURY (commercial 6.8x51mm) cartridges. The barrel can be capped by a suppressor (SIG SLX, which will be standard-issue equipment for the XM5 package) for clandestine operations and the over-frame Picatinny rail can mount various tactical accessories to suit the mission need. The charging handles are set at both the left-side (non-reciprocating) and rear-of-frame (AR-15-style) positions.

Depending on configuration, the MCX-SPEAR has an overall length of 34.1 inches with a barrel measuring 13 inches long. Weight with the magazine inserted is 8.38lb.

Further trials involving the MCX-SPEAR will be conducted by the Army under the "XM5" designation and, it is assumed, it will enter service as the "M5". The SIG product beat out competitors from Beretta, Desert Tech, Fabrique-Nationale, and Textron and will be chambered in the 6.8x51 SIG FURY cartridge.

Final forms of the in-service gun will incorporate a ballistics-calculating Fire Control System (FCS) with integrated laser range-finders, direct-view optics, as well as magnifiers. Vortex Optics was selected to provide this component with its "XM157 NGSW-FC" entry.©MilitaryFactory.com
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April 2022 - The U.S. Army on April 19th, 2022 selected the SIG-Sauer MCX-SPEAR line to succeed its aging line of M4 assault weapons through the Next Generation Squad Weapons program.



Service Year

United States national flag graphic
United States


Modular Assault Carbine

SIG-Sauer, Incorporated - USA
(View other Arms-Related Manufacturers)
National flag of the United States United States (planned)
(OPERATORS list includes past, present, and future operators when applicable)
Automatic Function
Features a mechanical function to automate the firing action.
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.
This weapon is either inherently silent/suppressed or can be made so through special assembly added at the muzzle, specialized subsonic ammunition or a combination of both.

Despite its size / weight, the product can be transported by foot infantry.
Inherent ability to provide suppression capabilities against target / target area.
Supports silenced / suppressed actions - by way of silencer, suppressor, or subsonic ammunition - for clandestine operations.
Internal action allows release of single round per trigger pull, actuating a semi-automatic loading mechanism for successive shots.
Internal action allows release of multiple rounds with a trigger pull in quick succession.
An automatic, or pseudo-automatic, function is built into the system, allowing for repeat firing to be achieved.
Supports mounting of optics (scopes) to aid in accuracy for ranged fire.
Supports 'iron sights' allowing for inherent accuracy in ranged fire.
Aiming can be aided by use of a bipod support assembly, either as an integral part of design or option.
Design allows for user adjustability of certain components for customization.
Design offers mounting points for external, after-market hardware including laser aimers, flashlights, scopes, and grips.

Overall Length
866 mm
34.09 in
Barrel Length
330 mm
12.99 in
Empty Wgt
8.38 lb
3.80 kg

Onboard FCS; Various Optics.


Short-Stroke Gas Piston; Rotating Bolt; Selective-Fire

Rotating Bolt
System utilizes internal mechanism to lock the breech or rear barrel assembly prior to firing.
(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)


6.8x51mm SIG FURY

Rounds / Feed

20-round detachable box magazine.
Cartridge relative size chart
*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
1,700 ft
(518 m | 567 yd)
Muzzle Velocity
2,900 ft/sec
(884 m/sec)

M5 - U.S. Army in-service designation.
XM5 - Developmental designation.
MCX-SPEAR - Original SIG product model designation.

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Images Gallery

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Image of the SIG-Sauer M5 (XM5)
Image from official SIG Sauer marketing materials.
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Image of the SIG-Sauer M5 (XM5)
Image from official SIG Sauer marketing materials.
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Image of the SIG-Sauer M5 (XM5)
Image from the United States Army; Public Release.

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