How the U.S. Army’s M250 Machine Gun Compares to the M249 as the Service Adopts 6.8 mm Firepower.

The U.S. Army has formally type classified the M7 rifle and M250 automatic rifle, authorizing broad fielding across close combat units and confirming the M250 as the successor to the M249 SAW. The move signals a shift toward higher-energy 6.8×51 ammunition and sensor-driven precision at the squad level.

The U.S. Army’s Program Executive Office Soldier confirmed on 21 May 2025 Type Classification Standard for the M7 rifle and M250 automatic rifle, clearing both weapons for broad fielding across the Close Combat Force and formally designating the M250 as the successor to the M249 Squad Automatic Weapon in frontline units. This is an opportunity to compare the two rifles and explain what the new one brings to the U.S. Army compared to the old version, as the U.S. Army did in a video posted on YouTube.
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The U.S. Army's new M250 light machine gun delivers high-energy 6.8x51 mm firepower with a lighter chassis, suppressor-optimized design, and integrated use of the XM157 fire-control optic, giving squads greater lethality and precision at extended ranges (Picture source: U.S. DoW).

The M249 SAW, a U.S. license-built FN Minimi, has anchored American squad firepower since 1984, seeing combat from Panama and the Gulf War through Somalia, Iraq, Afghanistan, Syria, and today’s advisory deployments. Gas operated with a long-stroke piston and rotating open bolt, it fires 5.56×45 mm NATO from 100 or 200 round M27 disintegrating belts or emergency 30 round rifle magazines. A standard SAW weighs roughly 7.5 kg empty, about 10 kg with a 200-round drum, and measures around 40.8 inches with a 465 mm barrel, delivering a cyclic rate near 750–850 rounds per minute and muzzle velocity around 915 meters per second. Its quick-change, cold-hammer-forged, chrome-lined barrel allows sustained fire at 85 rounds per minute, with rapid-fire peaks at 200, provided crews adhere to barrel-swap drills taught in TC 3-22.249 and Marine Corps manuals.

Where the M249 reflects late Cold War thinking about sheer volume of fire, the M250 embodies the Next Generation Squad Weapon logic of overmatch against armored peer adversaries at 500 to 600 meters and beyond. The SIG Sauer-built M250, derived from the LMG 6.8, is a belt-fed, gas-operated, open-bolt light machine gun chambered for the 6.8×51 mm Common Cartridge, commercially .277 Fury. Army specifications list a 17.5-inch barrel, overall length about 36.8 inches bare or 41.9 inches with suppressor, and a weight of roughly 13 pounds with bipod, 14.5 pounds suppressed, at a cyclic rate close to 800 rounds per minute. The weapon is built around AR-style ambidextrous controls, a side-opening feed cover, a reinforced free-floating M-LOK handguard, and a dedicated suppressor that is treated as part of the system rather than an add-on.

The real revolution sits in the ammunition. Standard 5.56 NATO ball from the M249 offers good controllability and high magazine depth but modest retained energy at 600 meters, especially against modern plates. The 6.8×51 mm hybrid cartridge used in the M250 couples a brass body to a steel case head, allowing chamber pressures around 80,000 psi and velocities approaching or exceeding 900 meters per second, more than doubling downrange energy compared with legacy 5.56 loads. U.S. training documents put a 200-round 5.56 belt and drum at about 6.92 pounds, while publicly released M250 data lists a 100-round 6.8 belt pouch at roughly 6.77 pounds. In practice, each 6.8 round weighs almost twice as much and hits much harder, so gunners trade 600 rounds of 5.56 for perhaps 400 rounds of 6.8 at slightly higher carried weight but dramatically greater terminal effect.

Mechanically, both guns are open-bolt, belt-fed light machine guns, yet their architecture and sustainment concepts diverge. The M249’s two-position gas regulator, hydraulic-buffered stock, and truly quick-change barrel were designed for classic light machine gun roles, including long bursts from tripods. By contrast, Army descriptions of the XM250 stress that its 17.5-inch barrel is not a traditional quick-change unit, with the service accepting reduced sustained-fire capability in exchange for lower weight and a suppressor-optimized, stiffer barrel. Industry has since shown XM250 variants with quick-change barrels at AUSA, underscoring an ongoing debate inside the force over whether future increments should recover heavier sustained-fire performance. SIG has not published barrel-life figures, but catalog language on related 6.8 platforms emphasizes chrome-coated, cold-hammer-forged barrels designed specifically to survive high-pressure 6.8×51 ammunition, suggesting similar metallurgy on the M250 family even if exact numbers remain classified or proprietary.

The most profound tactical difference appears at the optic. For decades, many M249s ran with simple day optics or iron sights, and the gun’s doctrinal strength was wide-beaten zones and 85 rounds per minute of sustained fire to pin insurgents in alleyways or wadis. The M250 is designed from the outset to pair with the XM157 fire-control, a rugged 1–8× optic that folds a laser rangefinder, ballistic calculator, atmospheric sensors, digital compass, visible and IR lasers, and a heads-up corrected aiming display into one unit. Open-source accounts from Army trials and industry test events describe a surprisingly smooth recoil impulse for such a powerful round, with shooters able to hold five to seven-round bursts on steel at medium range while relying on the optic to correct for drop and wind. In doctrinal terms, the automatic rifleman becomes a precision suppressor, tasked with fast, high-probability hits on exposed teams rather than carpeted fire over a wide frontage.

Globally, the M249’s parent design, the FN Minimi, remains the dominant 5.56 light machine gun, built under license and serving as Canada’s C9, Australia’s F89, Sweden’s Ksp 90, Britain’s former L108A1, and in dozens of other armies and police units. The M250, by contrast, is at the start of its export life. Beyond U.S. Army and National Guard close-combat formations, the Israel Defense Forces have reportedly acquired a 7.62×51 mm variant of the design as a lighter, more agile alternative to the Negev, a significant endorsement from a force with hard combat experience. NATO as a whole is watching the NGSW family closely, but analysis from European officers suggests that alliance-wide 6.8×51 adoption, if it happens at all, will be gradual and heavily conditioned by budgets and logistics rather than pure performance.

The M249 and M250 are not simply two generations of the same gun but embodiments of two different eras of squad fire design. The SAW gave U.S. infantry light ammunition, large belts, and forgiving sustainment at the cost of armor penetration and reach. The M250 couples a high-pressure 6.8×51 cartridge, advanced fire-control, and a lighter chassis into a tightly integrated package that assumes better sensors and marksmanship in exchange for fewer but far more decisive rounds.