SIG Sauer NGSW-R MCX Spear assault rifle (USA)

The MCX Spear assault rifle is being developed by American division of international SIG Sauer gun making company under NGSW-R – “Next Generation Squad Weapon – Rifle” program, funded by US Army.


SIG Sauer NGSW-R MCX Spear assault rifle
SIG Sauer NGSW-R MCX Spear assault rifle


This highly ambitious program is intended to equip American infantrymen with new rifle and squad automatic weapon / light machine gun, both firing new, high-performance ammunition. Ultimate goal is to deliver squad small arms system, capable to defeat modern body armor at extended ranges and produce improved lethality, compared to existing 5.56mm small arms system. Requirements for NGSW program call for an entirely new cartridge, firing government-designed bullet with caliber of 6.8mm and weight or about 135 grains / 8.8 grams, with muzzle velocities of about 3000 fps / 915 m/s or even faster. These requirements, especially from a relatively short assault rifle barrel, call for very high bore pressures, which in turn would result in powerful muzzle blast and significant felt recoil. As a result, special type of sound suppressor is a must for these weapons, to help to attenuate “magnum” level muzzle blast and tame recoil.

Since particulars of the cartridge design are left out to contenders, SIG Sauer decided to go along with hybrid cartridge case design, in which case walls are made from brass, and the cartridge base is made from some other, lighter metal, such as steel or aluminum alloy. This design allows to retain backward compatibility with traditional ammunition, and offer weight savings of about 20-30% per empty case, compared with current style all-brass cases.

Current plans call for NGSW program winner to be announced by 2022, but with previous similar programs like SPIW, ACR or OICW in mind we shall wait and see for the results. At the present time all NGSW contenders, including SIG Sauer MCX Spear assault rifle, are still in prototype form.

SIG Sauer NGSW-R MCX Spear assault rifle is based on the popular SIG MCX rifle platform, but with certain upgrades. Gun is operated using traditional short stroke gas piston; gas system has manual regulator with two settings. Barrel is locked using a rotary bolt, and bolt return spring is located in the upper receiver, above the bolt group. To reduce peak recoil to comfortable levels, entire barrel / barrel extension / bolt assembly can recoil inside the receiver against a special buffer, located below and to the rear of the generally cylindrical barrel extension which contains bolt group. Firing controls are generally similar to M16 rifle / M4 carbine, although SIG Sauer NGSW-R MCX Spear prototype features additional non-reciprocating folding charging handle on the left of the receiver, besides “M16 standard” T-shaped handle at the rear. Ammunition is fed from 20-round box magazines, made from plastic, and barrel is normally fitted with specially designed sound suppressor, also developed by SIG Sauer. All sights are installed using integrated Picatinny rail located on the top of receiver and forend.


patent diagram showing recoil attenuation arrangement in rifle, by SIG Sauer
patent diagram showing recoil attenuation arrangement in rifle, by SIG Sauer




Caliber 6,8х51
Length, mm ~ 900 (with suppressor)
Barrel length, mm 330
Weight, kg ?
Rate of fire, rounds/minute ?
Magazine capacity, rounds 20