April 22, 2022
By Eric R. Poole
Following a media leak, the U.S. Army confirmed the announcement on Tuesday, April 19, 2022, that SIG Sauer was selected to provide the Next Generation Squad Weapon (NGSW). SIG Sauer was awarded a 10-year contract to deliver the XM5 Rifle and the XM250 Automatic Rifle, which chambers SIG Sauer’s new high-pressure and high-velocity 6.8x51mm hybrid cartridge. This information trails the January 2022 announcement that Vortex won the NGSW Fire Control (NGSW-FC) program, designated “XM157.”
The initial order is a contract worth $20.4 million. Funding was approved by the U.S. Congress in a spending bill during the first week of April 2022. Speculation of SIG Sauer’s win started with the public information request for the allotment of funds by Congress for the “M5 Carbine” and the “M250 belt-fed machine gun” ahead of the announcement. Knowing that LoneStar Future Weapons’ NGSW-AR submission was not belt-fed — and SIG Sauer’s NGSW-AR is — keen speculators were allegedly tipped off to the result. The U.S. Army aims to procure 30,000 NGSW systems in 2023.
Guns & Ammo has provided updates to the NGSW program since it began in 2018. The first prototype tests began in Spring 2021. A detailed look at SIG Sauer’s submissions to replace the U.S. Army’s M4A1, M249 SAW and the 5.56 NATO appeared after an exclusive test-fire, which was published in the September 2021 issue of Guns & Ammo.
The NGSW program was centered around the need for an unconventional cartridge loaded with a bullet designed to perform at unusually high velocities. The 6.8mm (.277 in.) projectile was designed by Picatinny Arsenal. The round is believed to be based on the hard-target penetrating performance of the military Enhanced Performance Round (EPR) loaded in the 5.56mm M855A1 cartridge, but specifics have been shrouded in secrecy.
Using the 6.8mm bullet, NGSW candidates were asked by the U.S. Army’s program managers to propel the 6.8 at a certain velocity, which resulted in high chamber pressures that exceeded commercially acceptable numbers. SIG Sauer replied, “Challenge accepted.” The 6.8 Hybrid cartridge was designed backwards compatible with the 7.62 NATO. This protected the viability of the cartridge if the military declined the weapon platforms, but it also meant that manufacturing is compatible with tooling already in use to manufacture conventional ammunition such as the 7.62 NATO.
To safely harness the pressure, SIG Sauer developed its 6.8mm Hybrid cartridge with a unique stainless-steel alloy rim joined to a brass-case body. The brass case isn’t as thick as a 7.62 round’s, which allows it to accept a larger charge of propellant. As a nod to SIG Sauer’s achievement in its hybrid case design, the anticipated commercial version of the round, known as the “.277 Fury,” received SAAMI approval in November 2021. From a 16-inch barrel, the .277 Fury was certified to propel a 135-grain bullet to more than 3,000 feet per second (fps) and a 140-grain bullet to 2,950 fps. The resulting chamber pressure is near 80,000 psi, which exceeds even the 65,000-psi rating of the .338 Lapua Magnum. Muzzle energy translates to about 2,700 foot-pounds (ft.-lbs.). Not since the 19th-century development of the self-contained cartridge has ammunition design advanced this dramatically.
The XM5 Carbine is based on a 7.62 NATO-pattern rifle chambered for the 6.8x51mm. The commercial variant has been labeled as the MCX-SPEAR. A few semiautomatic samples were manufactured and sold through select dealers in January 2022, which advertised an adaptable multi-caliber rifle that could accept barrels chambered in .277 SIG Fury, 6.5 Creedmoor and 7.62 NATO. Though the layout of controls and certain features are familiar to users of AR- and MCX-pattern firearms, the side-charge operating system is unique to the MCX-SPEAR. The upper receiver and barrel were specifically designed to safely harness the pressures of the new hybrid-case cartridge.
The XM250 Automatic Rifle is an entirely new machine gun that operates using a belt of 6.8x51mm rounds organized in a disintegrating belt. Employing the XM250 will be familiar to machine gunners already assigned to operate the M249, but the feed tray can be converted to feed from either side. Unlike the M249, the XM250 controls complement the familiar layout of the AR-pattern M4/M16 lower receiver, including controls of the XM5.
Finalists for the NGSW program also included LoneStar Future Weapons, which chambered True Velocity’s composite-cased 6.8 TVC cartridge in its bullpup-configured RM277. A complete overview with detailed pictures of the RM277 and the 6.8 TVC cartridge appeared in the October 2021 issue. It can be read here. Textron also submitted an entry but reportedly withdrew in November 2021.
G&A’s testing of the NGSW prototypes revealed that the 6.8 Hybrid cartridge produces stout felt recoil in both the XM5 and the XM250. Therefore, it is unlikely that these systems are intended to be issued to every soldier as a primary weapon system. However, the 6.8 round did meet the U.S. Army’s performance requirements, so expect to see it adapted to other platforms.
The Defense Department’s arsenal upgrade is not complete. The U.S. Army announced in March 2022 that it seeks a 6.8mm conversion kit for existing M240 machine guns that would retain the serialized receivers. Also, there are Request for Proposals (RFP) for new .50-caliber ammunition, an update to the existing inventories of 5.56-chambered M4 carbines, and a Medium Machine Gun in .338 Norma Magnum (MG338). Additionally, the U.S. Army awarded Winchester $20 million in contracts to assist in the ammunition production of the 6.8 cartridge at Lake City. Fielding of these next-gen systems is certain to revolutionize modern warfare in America’s favor.
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