SIG SAUER NGSW-AR XM250 Automatic Rifle / machine gun (USA)

The SIG SAUER NGSW-AR light machine gun, which as of April 19, 2022, was also assigned the official designation XM250 Automatic Rifle, is a lightweight but powerful squad support weapon, intended to replace old M249 SAW machine guns in the Squad Support / Automatic Rifle role within front-line infantry units of US military. The SIG SAUER NGSW-AR XM250 Automatic Rifle appears to be a part of the winning team that emerged from the recent US Next Generation Squad Weapon completion, along with the SIG SAUER MCS SPEAR NGSW-R rifle. Currently US Military plans to purchase both SIG SAUER weapons for extensive field testing, which, eventually may, or may not result in the official adoption and fielding of the new system.

 

SIG SAUER NGSW-AR machine gun / XM250 Automatic Rifle

SIG SAUER NGSW-AR machine gun / XM250 Automatic Rifle

 

The SIG SAUER NGSW-AR machine gun / XM250 Automatic Rifle fires the same powerful 6.8x51mm SIG composite case ammunition as the SIG SAUER MCS SPEAR NGSW-R rifle. This ammunition, also developed by the SIG SAUER, is the core part of the NGSW program, along with the XM157 Fire Control, a ruggedized advanced fire control system that increases accuracy and lethality for the close combat force. This new ammunition is planned to greatly extend the effective range of the small arms fire, compared to the current 5.56x45mm M855A1 ammunition, but at the cost of increased ammunition weight, recoil, and muzzle blast, which requires the routine use of the sound moderator. It is yet to be seen if the system will live up to the expectation of the US military brass and grunts.

 

SIG SAUER NGSW-AR machine gun / XM250 Automatic Rifle

SIG SAUER NGSW-AR machine gun / XM250 Automatic Rifle

 

The SIG SAUER NGSW-AR machine gun / XM250 Automatic Rifle is a gas-operated, belt-fed machine gun. It uses a patented recoil-mitigation system where the entire barrel assembly with its extension, gas system, and bolt group is allowed to recoil inside the receiver against the hydraulic recoil mitigation buffer. This system was initially developed for the experimental LWMMG-338 machine gun, developed by General Dynamics. Later, the key designer of this system, engineer David Steimke, went to work for SIG SAUER where he developed a very similar SIG MG-338 machine gun. So, the SIG NGSW-AR is more or less a scaled-down version of these earlier weapons, with some noticeable changes.

The SIG SAUER NGSW-AR machine gun uses rotary bolt locking, and the bolt engages the barrel extension. Gun fires from the open bolt, and, unusually for weapons of this class, can fire both continuous bursts and single shots. The gas system is located below the barrel and features a short-stroke piston with a manual gas regulator. The air-cooled barrel can be quickly replaced if overheated or worn. In most cases, barrels are fitted with removable sound and flash suppressors (moderators), which are required due to the high pressures of the military-grade 6.8mm ammunition.

 

SIG SAUER NGSW-AR, patent diagram

SIG SAUER NGSW-AR, patent diagram

 

The SIG SAUER NGSW-AR machine gun / XM250 Automatic Rifle uses disintegrating steel belts with open, push-through pockets. The belt feed cover, rather unusually, opens to the right rather than up and forward, as on most modern machine guns. The belt feed direction is from the left side only, and the new belt can be loaded without opening the feed cover when using starter tabs. For the automatic rifle role, belts can be carried and fired from the detachable semi-rigid containers that are attached to the bottom of the receiver. The capacity of containers is 30, 50, 100, and 200 rounds. Standard loadout for an automatic rifleman with an XM250 is four 100-round belt containers, each weighting about 3.08 kg.

In its typical configuration, the SIG SAUER NGSW-AR machine gun / XM250 Automatic Rifle uses a pistol grip with trigger and manual safety/selector, a side-folding, and adjustable shoulder stock, and a folding bipod that is attached to the front end of the receiver. The top of the receiver is provided with the integrated continuous Picatinny rail, which can accept a wide variety of sights and other accessories, such as IR/Night sights, optical and red dot sights, or the newest computerized fire control systems.

 

SIG SAUER NGSW-AR specifications:

  • Caliber: 6.8x51mm
  • Overall length: 1064 mm (with suppressor)
  • Barrel length: 444 mm (17.5″)
  • Weight, empty: ca. 6.6 kg (14.5 lbs) with suppressor and bipod
  • Feed: belt