LMT MK24: SOCOM's SCAR-H Replacement Fires 7.62 NATO and 6.5 CM

The LMT MK24 is U.S. Special Operations Command's designation for the Mid-Range Gas Gun, Assault (MRGG-A), a 14.5-inch AR-pattern carbine that swaps between 7.62x51mm NATO and 6.5mm Creedmoor in about a minute. SOCOM's program manager confirmed initial deliveries will begin before the end of fiscal year 2026, which closes September 30. The rifle ends the operational career of the Mk17 SCAR-H, the 7.62 carbine SOCOM first fielded to combat units in 2009.

LMT Defense, based in Eldridge, Iowa, won the MRGG-A contract in August 2025 under a 10-year indefinite-delivery, indefinite-quantity agreement with a $92 million ceiling. The contract scope covers rifles, spare parts, accessories, user training, and engineering modifications, which is what SOCOM and LMT both describe as a deployment package rather than a bare rifle order. The MK24 itself weighs approximately 9.2 pounds without optic, accessories, or magazine.

SOCOM picked the MK24 to consolidate two problems the SCAR-H could not solve. The first is training and parts overhead. The SCAR-H uses its own short-stroke piston operating group, its own ergonomics, and its own accessory language, none of which transfer cleanly from the M4 carbine that every other SOF rifle and most partner-force rifles already use. The MK24 keeps M4-pattern fire controls, an AR-pattern manual of arms, and AR-standard stock, grip, and rail interfaces, so an operator coming off an M4 picks it up without retraining.

The second is caliber flexibility. SOF teams routinely operate alongside partner forces whose ammunition stocks are 7.62 NATO, while their own engagement profile increasingly demands the ballistic reach of 6.5 Creedmoor past 600 yards. The MK24 swaps between the two using LMT's quick-change barrel system, which SOCOM and LMT both describe as a roughly one-minute operation with zero retention across swaps. A single weapon now covers the 7.62-only logistics case and the 6.5 CM extended-range case without a second rifle. For the ballistic side of why SOCOM keeps standardizing on 6.5 CM for DMR work, see our 6.5 Creedmoor tactical guide.

The MK24 is built on LMT's Modular Weapon System (MWS), the same architecture as the civilian LMT MWS MARS-H and MRGG-A Reference Rifle. The upper is a monolithic MRP unit machined from a single 7075-T6 aluminum billet, which integrates the handguard rail into the upper receiver and eliminates the upper-to-handguard mating surface. That continuous rail is what gives the platform a single uninterrupted optics mounting surface, and it is also what enables the quick-change barrel system: the barrel locks into the upper through a factory barrel extension that retains zero across swaps.

The lower is the MARS-H, LMT's fully ambidextrous large-frame lower. Bolt catch, bolt release, magazine release, and safety all run from either side, which matters most in close-quarters work and for shooters who switch shoulders behind cover. Magazines are SR-25/DPMS pattern, the dominant family for 7.62 NATO and 6.5 Creedmoor AR-10s, so a single magazine inventory covers both calibers. The fire controls and overall manual of arms match the M4 carbine, which is the entire training argument for picking the MK24 over a SCAR replacement built on its own ergonomic language.

6.5 Creedmoor is the ballistic upgrade, 7.62 NATO is the logistics anchor. From a 14.5-inch barrel, 6.5 CM with a 140-grain match load leaves the muzzle at roughly 2,510 fps and stays supersonic past 1,200 meters, with about 28 percent less wind drift than .308 in a 10 mph crosswind. That extended-range advantage is why SOCOM already replaced .308 with 6.5 CM in the SR-25 and M110 DMR platforms in 2019, and it is the same logic driving the MK24's 6.5 CM barrel option for distance engagements.

7.62 NATO is what partner forces and host-nation logistics chains actually stock at scale. SOF teams routinely run alongside militaries whose ammunition supply is 7.62 NATO end to end, and a single-caliber 6.5 CM rifle would force operators to either carry their own ammunition forward or accept the round their partners actually have. The MK24's quick-change barrel removes that tradeoff. Inside 300 yards the two calibers behave similarly; past 600, 6.5 CM is meaningfully better, with recoil roughly 40 percent lower, which matters more in a semi-auto where fast follow-up shots are a core advantage of the platform.

For buyers who do not want the SBR paperwork of the MRGG-A Reference Rifle, the LMT MWS MARS-H 6.5 Creedmoor 20-inch is the non-NFA option from the same MWS family. It shares the monolithic MRP upper, MARS-H ambidextrous lower, and quick-change barrel system with the MK24, then trades the carbine barrel for a 20-inch stainless 1:8 5R that picks up roughly 100-200 fps on identical loads. UK and New Zealand military adoption of the MWS platform gives it the strongest QA validation in the 6.5 CM AR-10 segment. Use our rifle builder to spec optic, suppressor, and bipod choices around either MWS configuration.

The MK24 is the assault-variant carbine, not the full SCAR-replacement story. SOCOM split the Mid-Range Gas Gun program into two tracks: MRGG-A (Assault), which LMT won in August 2025 and which produces the 14.5-inch MK24, and MRGG-S (Sniper), which Geissele Automatics won in 2023 under a $29M ceiling and which produces a 20-inch 6.5 Creedmoor precision rifle sold civilian as the Geissele VSASS MRGG MK1. The two tracks together cover the carbine and sniper roles the SCAR-H and SR-25/M110 families previously handled separately, with 6.5 CM as the common caliber across both.

The MK24 also lands in the same news week as FN's own SCAR-replacement strategy, since FN positioned the new FN ARKA as an AR-ergonomic accompaniment to the improved SCAR MK2 rather than as a SCAR replacement. The MK24 takes a different path to the same problem: SOCOM is not buying a new piston-AR, it is going to a DI MWS platform that already shares an ecosystem with the M4. For the LMT MRP upper architecture that underpins the MK24, see our coverage of LMT's Hybrid MRP uppers at SHOT Show 2026.

The LMT MK24 closes the SCAR-H chapter for SOCOM by collapsing two roles, partner-force-compatible 7.62 NATO carbine and 6.5 Creedmoor extended-range carbine, into a single rifle with a quick-change barrel and an AR-pattern manual of arms. LMT built the platform on the MWS architecture the company has been selling to civilians and US allies for years, which is why the deployed MK24 has direct civilian analogs in the catalog: the LMT MWS MRGG-A Reference Rifle for buyers who want the actual 14.5-inch SBR configuration, and the LMT MWS MARS-H 6.5 Creedmoor 20-inch for buyers who want the same monolithic upper and ambidextrous lower without the NFA paperwork.

The bigger story is what the MK24 says about US service-rifle direction. Two SOCOM contracts (MRGG-A to LMT, MRGG-S to Geissele) have now standardized on 6.5 Creedmoor as the long-range cartridge of choice, on AR-pattern ergonomics as the SOF baseline, and on monolithic-upper modularity as the architecture. The SCAR-H's retirement after 17 years of operational service marks the end of the parallel-platform era for SOCOM. To see how 6.5 CM AR-10s line up at consumer price points, see our best 6.5 Creedmoor rifle guide, or compare LMT MWS configurations against the Geissele and Daniel Defense alternatives.