US Special Ops Fields Caliber-Swapping MK24 Rifle For 7.62 Combat And 6.5 Range

Authored by Aamir Khollam via Interesting Engineering,

A new rifle heading to U.S. special operations forces can switch between 7.62mm NATO and 6.5mm Creedmoor ammunition in roughly a minute, giving operators a way to adapt to changing mission requirements without carrying separate weapon systems.

The weapon, known as the MK24 Medium Range Gas Gun Assault (MRGG-A), will begin reaching units before the end of the fiscal year. U.S. Special Operations Command (SOCOM) selected the platform to replace the MK17 SCAR and awarded manufacturer LMT Defense a 10-year, $92 million contract last year. The rifle also supports SOCOM's broader effort to improve performance at longer ranges while maintaining flexibility in the field.

Built For Flexibility

The MK24's defining feature is its quick-change barrel system. Operators can swap between 7.62mm NATO and 6.5mm Creedmoor configurations in about a minute, allowing the weapon to adapt to different operational needs.

The requirement emerged from real-world deployment challenges. U.S. forces frequently operate alongside partner militaries that rely on different ammunition stocks. By allowing rapid caliber changes, the MK24 can continue using widely available 7.62mm rounds while giving operators access to 6.5mm Creedmoor when missions demand greater accuracy at distance.

LMT Defense designed the rifle around a 14.5-inch barrel, creating a package closer in size to an M4 carbine. Despite its compact footprint, the weapon aims to deliver the performance expected from larger precision-focused systems.

Why 6.5 Creedmoor

The adoption of 6.5mm Creedmoor reflects years of testing by SOCOM as it evaluated alternatives to legacy military cartridges. The command examined nearly two dozen ammunition types and reportedly found that 6.5mm Creedmoor delivered some of the strongest overall performance at ranges approaching 1,000 meters.

That advantage has attracted growing interest across the military. While 7.62mm NATO remains a mainstay of U.S. forces, newer cartridges have demonstrated improved long-range accuracy and energy retention. The Army has already started introducing its Next Generation Squad Weapons chambered in 6.8x51mm as part of a similar modernization effort.

For SOCOM, the shift is not simply about replacing ammunition. The command has spent several years searching for weapon systems that can engage targets farther away while reducing logistical burdens on deployed units.

Expanding Long-Range Capabilities

The MK24 is one piece of a wider small-arms modernization program. In recent years, SOCOM has explored new rifles and machine guns capable of extending engagement distances beyond those of existing platforms.

Those efforts resulted in contracts for a new 6.5mm sniper rifle from Geissele Automatics and a lightweight machine gun chambered in .338 Norma Magnum from Sig Sauer. Although fielding of the machine gun has been paused, the programs reflect SOCOM's interest in cartridges that offer greater effectiveness at extended ranges while reducing system weight.

Officials involved with the program have highlighted the MK24's accuracy and adaptability as major advantages. Beyond replacing the MK17 SCAR, the rifle introduces a modular approach that allows a single platform to fill multiple roles. As fielding begins, the weapon will give special operations units the ability to move between 7.62mm combat loads and 6.5mm long-range configurations with minimal disruption in the field.