SIG Sauer M8

History

Sig Sauer was awarded the Next Generation Squad Weapon (NGSW) contract in April 2022. The program initially produced the M7 rifle and M250 automatic rifle, which were tested and fielded to multiple U.S. Army units. Soldiers reported concerns about the M7's weight, length, and component wear from the high-pressure 6.8×51mm Common Cartridge. In response, Sig Sauer developed a shorter carbine variant, initially designated XM8 and later M8. The Army approved procurement of the XM8 carbine on December 10, 2025, following extensive government testing including a full developmental verification test and a September 2025 Soldier evaluation involving the 101st Airborne Division, USASOC, and other units. Fielding of the M8 is scheduled to begin in December 2026 with selected units at Fort Bragg, North Carolina.

Design

The M8 is a carbine variant of the M7, measuring approximately 3.5 inches shorter and over one pound lighter than the full-length M7. It replaces the M7's folding stock with a fixed stock and adds rigidity to the handguard. Weight reduction was achieved through lightening cuts around the receiver and barrel, with careful attention to preserving barrel life and performance. The Army describes the M8 as the same weight as the M4A1 carbine, while Sig Sauer characterized the weight difference between the M4A1 and M8 as less than one pound. The M7 weighed more than eight pounds unloaded and nearly ten pounds with its suppressor, compared to the M4A1's 6.34 pounds unloaded.

The M8 is a gas-operated, magazine-fed weapon chambered in the 6.8×51mm Common Cartridge. It is equipped with the M157 NGSW Fire Control, a magnified 1-8x direct-view optic with display overlay, laser range finder, aiming lasers, and ballistic solver, incorporating Intra-Soldier Wireless (ISW) for communications with soldier-mounted subsystems. The lower receiver is the same serialized component used on the M7, allowing conversion of an M7 to an M8 carbine by replacing the barrel and handguard, a process Sig Sauer estimates at under five minutes.

Program status

Fielding of the M8 carbine is scheduled to begin in December 2026 with selected units at Fort Bragg, North Carolina. The Army has curtailed M7 procurement, with no additional M7s requested for Fiscal Year 2027; approximately 50,000 M7s have been delivered to the force. Options for the existing M7 inventory include reassignment to basic training or Guard and Reserve units, or conversion to M8 carbines using the shared lower receiver. The NGSW program continues with planned improvements including lightweight ammunition, 25-round magazines, alternate optics, and a thermal imager to supplement the M157 fire control.

Operators

• United States – U.S. Army; fielding of the M8 carbine begins December 2026, replacing the M4A1 as the standard carbine.

Specifications (M8 carbine)

General characteristics

• Caliber: 6.8×51mm Common Cartridge
• Operation: gas-operated, magazine-fed
• Stock: fixed
• Fire control: M157 NGSW-Fire Control (1-8x magnified direct-view optic with display overlay, laser range finder, aiming lasers, ballistic solver)

Dimensions and weight

• Length: approximately 3.5 inches shorter than the M7 rifle
• Weight: comparable to the M4A1 carbine (approximately 6.34 lb / 2.88 kg unloaded); over one pound lighter than the M7

Related equipment

• SIG Sauer M7 – full-length NGSW rifle; the M8 is its shorter carbine variant.
• M4A1 carbine – predecessor in the U.S. Army's close-combat carbine role.
• SIG Sauer M250 – NGSW automatic rifle; shares the 6.8×51mm Common Cartridge and is being fielded alongside the M8.