US Army designates M7 carbine variant as XM8 for faster handling in close combat.

The U.S. Army designated the carbine variant of its new M7 assault rifle as XM8 and assigned it the national stock number 1005-01-737-3402, formalizing its entry into its inventory under the Next Generation Squad Weapon (NGSW) program. 

The US Army has designated the short-barrel carbine variant of the M7 rifle as XM8 within the NGSW program, confirming its integration into the US Army's equipment inventory with a dedicated NSN. The carbine configuration reduces barrel length and weight to improve handling in close combat while maintaining compatibility with 6.8 x 51 mm ammunition.
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The shorter barrel of the XM8 reduces the muzzle velocity compared to the M7 barrel, but improves maneuverability in vehicles, buildings, and other confined environments, where longer weapons can limit the movement of soldiers. (Picture source: Army Recognition)

As reported by Soldier Systems on March 16, 2026, the U.S. Army designated the carbine variant of the new M7 rifle as XM8 and assigned it the national stock number 1005-01-737-3402, formalizing its entry into the inventory as a distinct short-barrel weapon within the Next Generation Squad Weapon (NGSW) program. The XM8 is configured with a 10-inch (254 mm) barrel and a base weight of 7.3 pounds (3.31 kg) without suppressor or optic, compared to 8.3 pounds (3.76 kg) for the M7 carbine with a 13.5-inch (343 mm) barrel, resulting in a 1.0 pound (0.45 kg) weight reduction. The XM8, fielded alongside the M7, incorporates design changes aimed at reducing weight and length while maintaining compatibility with the 6.8 x 51 mm composite case ammunition.

The assignment of an NSN confirms readiness for procurement, storage, and distribution within Army supply systems, while retaining compatibility with the same ammunition and operating system as the M7. The XM8 carbine, intended for close combat forces, incorporates a set of modifications relative to the M7 assault rifle that are limited in scope but measurable in effect. The barrel length reduction from 13.5 inches to 10 inches decreases overall weapon length and shifts the center of gravity rearward, which can improve handling during rapid target acquisition in confined spaces. The barrel is also tapered, reducing forward mass and contributing to the total 1-pound weight decrease when measured without accessories.

The upper receiver group has been modified to remove material not required for structural performance, further contributing to weight reduction. The elimination of the side-folding buttstock used on the M7 removes hinge and locking components, replacing them with a fixed telescoping stock that maintains adjustability while reducing mechanical complexity. These changes do not alter the core operating mechanism or ammunition type, indicating that the XM8 is a derivative configuration optimized for a specific operational niche rather than a redesign. Previously known as the XM7, the M7 assault rifle is the U.S. Army’s new standard individual weapon selected under the Next Generation Squad Weapon (NGSW) program.

Derived from the SIG MCX-SPEAR and chambered in 6.8 x 51 mm (.277 Fury), the rifle entered service in 2022 under the XM7 designation before being type classified as M7 in May 2025, confirming compliance with operational, safety, and sustainment requirements. The weapon is designed to replace the M4 carbine within close combat forces, including infantry, cavalry scouts, combat engineers, and forward observers. Initial fielding began in March 2024 with the 1st Battalion, 506th Infantry Regiment of the 101st Airborne Division, followed by additional deployments such as within the 25th Infantry Division in January 2026. Procurement planning allows for up to 107,000 rifles over a decade, with distribution limited to combat units.

The NGSW program also includes the M250 automatic rifle to ensure caliber and system commonality at the squad level. The M7 operates using a short-stroke gas piston system with a rotating bolt, a configuration selected to reduce internal fouling and improve reliability under sustained firing conditions compared to direct impingement systems. The rifle is equipped with a free-floating reinforced handguard using the M-LOK interface, allowing direct attachment of accessories without affecting barrel harmonics. The standard barrel length is 330 mm, with an alternative 267 mm configuration for shorter variants, and the weapon supports suppressor use as part of its standard configuration. The weapon integrates advanced optics, including the M157 fire control optic, designed to improve target acquisition and engagement accuracy.

Feeding is provided by detachable SR-25 pattern box magazines with a standard capacity of 20 rounds and an optional 25-round configuration. The 6.8 mm also imposes a different load profile on individual soldiers compared to previous weapons due to both weapon weight and ammunition characteristics. For the M7, a standard combat load consists of 140 rounds carried in seven 20-round magazines, with a total weight of 4.4 kg. This represents a significant reduction in carried ammunition compared to the M4 configuration, where soldiers typically carried 210 rounds, but with increased per-round effectiveness. However, the total carried load for weapon and ammunition is higher, with an increase of about 1.8 kg compared to the previous standard.

The ballistic performance of the M7 is defined by the 6.8 x 51 mm cartridge, which produces a muzzle velocity of 915 m/s in the 330 mm barrel configuration and approximately 854 m/s in shorter barrel variants. This cartridge generates higher muzzle energy than 5.56 mm ammunition, improving effectiveness against modern body armor and increasing lethality at extended ranges. The design requirement for this cartridge emerged from assessments that adversary protective equipment and engagement distances had reduced the effectiveness of both 5.56 mm and 7.62 mm systems. The composite case construction reduces cartridge weight compared to brass, partially mitigating the increased weight associated with a larger caliber round. The M7 has an unloaded weight of 3.80 kg and reaches 4.46 kg when fitted with a suppressor, reflecting the additional mass associated with both the suppressor and reinforced components.

Overall length is 914 mm with a suppressor in the standard configuration, while shorter variants with a 267 mm barrel measure 851 mm with a suppressor attached. Operationally, the M7 is intended to extend the effective range of standard infantry fire and increase the proportion of soldiers capable of engaging targets beyond 300 meters. Previous force structures relied on a limited number of weapons, such as machine guns or designated marksman rifles, to achieve effective fire at those distances. The M7 shifts this capability toward the individual rifle level, increasing distributed lethality within the squad. This change affects both engagement tactics and ammunition logistics, as all primary rifles within the unit share the same caliber. More trivially, the XM8 designation has historical precedent in an earlier U.S. Army program from the early 2000s, which involved a 5.56 mm rifle derived from the Heckler and Koch G36, but that program was canceled prior to adoption, and the weapons were not fielded.

Written by Jérôme Brahy

Jérôme Brahy is a defense analyst and documentalist at Army Recognition. He specializes in naval modernization, aviation, drones, armored vehicles, and artillery, with a focus on strategic developments in the United States, China, Ukraine, Russia, Türkiye, and Belgium. His analyses go beyond the facts, providing context, identifying key actors, and explaining why defense news matters on a global scale.