SIG MCX Spear: The U.S. Army’s Next Rifle?

By: Warren Gray

Copyright © 2021

“The real issue is that, primitive as they are, (they) have learned to keep out of rifle range.”

— British actor Alan Rickman, as Elliott Marston, in the film, Quigley Down Under, 1990.

Recent, combat experience in Afghanistan, Iraq, Somalia, and Syria has clearly demonstrated to the U.S. Army that the standard-issue, Colt M4A1 carbine and its 5.56x45mm NATO ammunition do not create sufficient, projectile velocity beyond 330 yards to effectively kill an adversary, while Taliban insurgents and other enemy sharpshooters have quickly learned to remain at distances of 650 to 850 yards from American troops, in order to exploit this obvious, combat weakness.

The 5.56mm cartridge has served its purpose admirably for more than a half-century, with the principal advantages of excellent controllability and very low recoil. But it was designed for the dense jungles of Vietnam, where enemy troops were small in stature, and the typical engagement range was a mere 60 yards or less. Also, the urbanization of American society meant that fewer new recruits had any experience with firearms, and were bothered by the stout recoil of older rifles, such as the M1 Garand or M14. Currently, 83 percent of Americans live in urban areas, according to the U.S. Census Bureau, compared to only 57 percent during World War Two, so they now tend to have far less experience with hunting, recreational shooting, and firearms recoil.

As early as October 1993, during the ill-fated, “Black Hawk Down” incident in Mogadishu, Somalia, the glaring deficiencies of the 5.56mm round drew scathing criticism from Delta Force operators in battle. Master Sergeant Paul Howe, in particular, noted that his 5.56mm, M855, 62-grain, green-tip rounds were passing right through enemy combatants without much effect. The small-diameter bullets made neat, clean holes, but unless they struck the heart or spine, they were simply insufficient to stop a hostile insurgent in his tracks. Howe complained he had to hit an enemy soldier “five or six times, just to get his attention.”

As an interim measure to increase combat firepower and the effective range of rifles, small quantities of powerful, Springfield Armory M14 battle rifles in 7.62x51mm NATO (.308-caliber) have been taken out of mothballs and reissued, and the FN Mk. 17 SCAR-H rifle has been produced in the same caliber for U.S. special operations forces, but the recoil is still substantial, compared to that of a 5.56mm weapon.

Accordingly, the Army has initiated a highly-ambitious program, the Next-Generation, Squad Weapon-Rifle, or NGSW-R, with the goal of providing American infantrymen with a new rifle and new light machine gun, capable of firing high-performance ammunition to defeat enemy body armor at extended ranges, and produce improved lethality. The program requirements call for an entirely-new, 6.8x51mm cartridge, firing a government-designed bullet at very high velocity.

It specifies a 135-grain (military version) or 140-grain (Sierra GameKing hunting version), low-drag, open-tip match (OTM, military version only) or ballistic-tip (Sierra-tipped, hunting version) projectile, fired at 3,000 feet per second from a 16-inch, SIG Cross rifle barrel (about 2,820 fps from a 13-inch barrel), with 2,694 foot-pounds of muzzle energy, although the Spear’s actual barrel is 13 inches long. Effective range of the new, SIG ammunition, introduced in 2019, is 1,320 yards, a whopping, 50-percent improvement over the venerable, 7.62mm NATO round in current service.

The MCX design is totally modular, though, and the 16-inch barrel from the Cross hunting rifle could certainly be added later, if desired. The comparatively-short barrel length is the result of proven, combat experience with the FN Mk.17 SCAR-H CQC (“Close-Quarters Combat”) carbine in the hands of U.S. special operations forces, and the HK417A2 carbine used by British Special Forces, both chambered in 7.62mm NATO, and both utilizing 13-inch barrels.

The powerful SCAR-H has proven to be enormously popular with American special operations forces, including the U.S. Army Rangers, U.S. Navy SEALs (now their standard weapon), Marine Corps Special Operations Command (MARSOC), Air Force Special Operations Command (AFSOC), and in smaller quantities with the U.S. Army Special Forces and even Delta Force.

In contrast, 7.62mm NATO ammunition utilizes a 147-grain, full-metal-jacket (FMJ) bullet at 2,800 fps and 2,559 ft./lbs. energy and 60,000 psi of case pressure from a 24-inch, test barrel, with an effective range, per the U.S. Army, of 880 yards. The new, .277 SIG Fury cartridge is based upon the 7.62mm design, with the same case length and head diameter, but it holds a smaller bullet, driven at an unprecedented, 80,000 psi of case pressure, using a proprietary, new powder blend.

This is obviously quite a powerful load, with substantial recoil, under normal circumstances, but SIG has introduced a two-position, gas-system regulator (for suppressed or unsuppressed firing) and a patented, recoil-reduction system with a special movable barrel group and rollback buffer to reduce recoil to manageable levels. There is also a new, MIL-SLX68-QD quick-detachable suppressor to tame the significant muzzle blast and flash. SIG Sauer USA claims that the overall, felt recoil of the Spear is comparable to that of a 5.56mm weapon, which is quite a remarkable achievement.

Last year, the U.S. Special Operations Command selected the FN Mk. 20S rifle in 6.5mm Creedmoor as its new, long-range, sniper rifle. Extensive testing of this cartridge, which is actually slightly less-powerful than the new .277 SIG Fury, compared to the 7.62mm NATO round, revealed that the 6.5mm round had less recoil, one-third longer effective range, and at a range of 1,000 meters, it had 30-percent more energy, 40-percent less wind drift, and double the hit probability, so the slightly-longer, 6.8x51mm SIG cartridge should exhibit very similar characteristics. SIG claims that the .277 cartridge exhibits six to nine feet less drop at 1,000 yards than the 6.5mm Creedmoor, while delivering 20 to 25 percent greater energy.

Within the coming year, by the first quarter of Fiscal Year 2022, the Army plans to select an NGSW-R replacement for all of its M4A1 carbines and M249 squad-automatic weapons in 5.56mm, and begin actually fielding the new firearms during the first quarter of 2023.

The three companies competing for this contract are SIG Sauer USA, with a fairly-conventional, classic, M4-style design (they call it the MCX Spear) with a 13-inch barrel and 20-round magazine, using hybrid (brass walls with a stainless-steel base, for 20-percent lighter weight, and higher chamber pressure), .277 SIG Fury cartridges, General Dynamics, with an RM277 bullpup design using a 20-inch barrel for greater muzzle velocity, and composite-cased cartridges, and Textron Systems, using advanced, case-telescoped cartridges.

At this point, it seems that SIG Sauer is the most-likely to win, because they already hold the Army contract for M17 and M18 service pistols, and their new Spear rifle is the most-traditional, least-radical candidate, and the simplest to produce. Of the three entries, SIG’s is also the only one designed, engineered, and produced entirely in-house by a single, American company, at their facilities in New Hampshire and Arkansas. “We are the only ones that haven’t partnered up with anyone,” said production manager Paul Snyder. “This is all SIG: SIG guns, SIG suppressors, SIG ammo, SIG accessories.”

The SIG MCX Spear features a traditional, short-stroke, gas-piston system, with layout and ergonomics generally similar to the Colt M4 carbine in current use, fully-ambidextrous controls, a free-floating, reinforced, M-LOK handguard, and folding, double charging handles (one on the left side, and one at the rear) so soldiers don’t have to take their hands off the pistol grip (as they must do on the M4 carbine) to charge the weapon.

There’s also a rotary bolt, plastic, 20-round magazines, Picatinny rails with folding, iron sights atop the receiver and forend, flat dark earth (FDE) exterior finish, an overall length of just over 30 inches (three inches shorter than an M4 carbine), and a fully-collapsible, side-folding buttstock, unlike the longer, M4 series. In addition, SIG offers their compact, TANGO6T 1-6x24mm zoom scope ($1,540) in FDE finish for the Spear, which is highly recommended for longer-range shooting.

The SIG MCX Spear is also a multi-caliber weapon, which can easily be produced, as required, in either 7.62x51mm NATO or 6.5x48mm Creedmoor. 7.62mm weapons are already proving to be two to three times as effective as 5.56mm rounds in stopping the enemy with a single shot, and the Spear with .277 SIG Fury ammunition should be significantly more powerful than that, with markedly longer range. The U.S. Army would be very wise to adopt the Spear as its new NGSW-R rifle, but even if they don’t in the long run, expect to see limited production runs of the SIG MCX Spear for our elite, special operations forces, who will surely appreciate the increased range, firepower, and lethality in combat.

Warren Gray is a retired, U.S. Air Force intelligence officer with experience in joint special operations and counterterrorism. He served in Europe and the Middle East, earned Air Force and Navy parachutist wings, and four college degrees, including a Master of Aeronautical Science degree, and was a distinguished graduate of the Air Force Intelligence Operations Specialist Course, and the USAF Combat Targeting School. He is currently a published author and historian. You may visit his web site at: warrengray54.vistaprintdigital.com.