Photos by Kenda Lenseigne

With apologies to Cormac McCarthy, the XM7 is the embodiment of the military’s tendency to be prepared to fight the last war it was in. Don’t get us wrong, SIG delivered everything the Army wanted, and did it with their usual efficiency — but if you ask the wrong question, you’ll get the wrong answer.

The MCX Spear is the civilian version of the XM7 —  the result of the Next Generation Squad Weapon program, colored by a decade-plus quest for the answer to U.S. infantry overmatched by people in Korengal without running water but armed with PKMs, who would initiate contact from outside the effective range of M4 carbines. 

This morphed into an effort to punch through commonly fielded body armor of our near-peer enemies, specifically Russia and China. To do this, the government, embodied by Picatinny Arsenal, developed a small arms projectile that looks very much like the M855A1 or M80A1 bullets, with a large, exposed, hardened penetrator. As far as we know, the bullet is still closely held and we’ve handled it only a couple of times, but the overall concept was to blast it out of a short-ish barrel at 3,000 fps and blow through ceramic or titanium plates out to 300 meters.

Why does this matter? In short, it doesn’t. 

Leaving aside the large area of soft, fleshy bits that aren’t covered by hard armor, we’re currently at an inflection point in modern warfare. As someone who’s recently carried a rifle in locales east of Poland, I can say with 100-percent certainty that the vast majority of casualties there are currently caused by artillery, mortars, and UAVs, rather than small arms. Which begs the question of why, if small arms are largely irrelevant in this environment, would you want to carry a rifle that’s heavy, bulky, and due to the weight of ammo it fires, of limited capacity. 

In scenarios where carbines are important — trench assaults, MOUT, and forests — then something lightweight, handy, and manageable is way more valuable than the ability to punch through body armor. If the first two rounds don’t drop a guy, dump the rest of the mag into his pelvis. Dudes we’ve worked with favor M4s, Bren 2s, and SCAR 16s in that order, and don’t see a compelling reason to change. In this world, 5.56 is adequate for the work they’re doing. But what would they know that the Chairman of the Joint Chiefs doesn’t?

Snipers, on the other hand, do indeed value the ability to crack plates. Recent advances in AP bullet technology give .308 the ability to penetrate Level IV armor at distance while still achieving decent accuracy from legacy platforms. But for field officers in the U.S. Army, that’s nowhere near as career-enhancing as selecting a new small arms system.

Which is not to say the Spear is a crappy rifle. It isn’t. It does everything the Army wanted and more. And as it’s going to be with us for at least as long as the M14, we should probably get to know it well.

SIG SAUER MCX-SPEAR SPECS:

• Caliber: 6.8×51
• Capacity: 20 rounds
• Barrel Length: 16 inches
• Overall Length: 37 inches
• Weight: 10.4 pounds (as shown) w/ 1-6×24
• MSRP: $5,000

SIG MCX-SPEAR .277 FURY	$4,200
SIG MCX-SPEAR .308 Win	$4,200
SIG MCX-SPEAR 6.5 Creedmoor	$4,200

UNDER THE HOOD

If you’re at all familiar with SIG’s MCX lineup, then you’ll be right at home with the Spear. Using the same short-stroke gas piston system as its little brother in 5.56 and .300 BLK, the 6.8×51 is a scaled-up version, feeding from SR25 magazines and keeping the AR-10 profile we’ve all become comfortable with. 

SIG deliberately designed their Next Generation Squad Weapon program entry to be the “easy button” contender for an establishment that grew up with the M16, eschewing polymer-cased or case-telescoped ammunition, as well as the bullpup configurations favored by other companies. 

Out front, there’s a QD attachment for a suppressor integrated into a 3-prong flash hider. 

The Spear is designed from the outset to be suppressed all the time, which, given the issued rifle’s 13-inch barrel and 80K psi ammo, is a good thing when it comes to service-related hearing loss. 

Our civilian-legal 16-inch gun has a heavy profile barrel under the handguards, which are secured to the upper receiver with the dovetail system found in the first two MCX generations, backed up with a Torx-headed bolt on both sides. 

This reduces flex and increases the accuracy of rail-mounted lasers. A two-position gas block allows the user to switch between “normal” and “adverse” settings; if you run the rifle on the “normal” setting without a can, you’ll end up with stoppages. The handguard and upper receiver allow for a continuous Picatinny rail at the 12 o’clock position, and there are seven rows of M-Lok slots to accommodate any accessories you might wish to add. 

Internally, the Spear uses the tried-and-true MCX operating system. A tappet piston located in the gas block whacks a carrier extension protruding under the handguard, driving the bolt carrier group to the rear and cycling the action. It has a number of advantages, one of which being that the two halves never actually touch, except for a fraction of a second when the piston drives the carrier rearward. 

At rest, they’re air-gapped, meaning the Spear has damn near a free-floating barrel — or at least as close as a piston gun can get. The carrier extension is hollow and provides a home for the extra-long recoil spring, ensuring it has plenty of room, rather than cramming everything into the confines of the upper receiver. 

In order to handle pressures that would make an AR-10 puke, SIG equipped the Spear with a hella stout bolt. Its seven lugs are much longer than usual (0.47 versus 0.31 inch) and absent of stress risers at the lug roots typically found in Stoner designs. In addition, the rear surface of the lug is angled, increasing surface area in contact with the barrel extension. 

Twin ejectors provide a measure of redundancy and ensure a very consistent ejection pattern, dropping cases into a neat pile about 13 feet from the gun. The bolt carrier has been extensively lightened to reduce reciprocating mass — by way of comparison, a DPMS-pattern BCG weighs 19.25 ounces, while the Spear’s tips the scales at 16.75, despite and including its carrier extension. 

Both upper and lower receivers are beautifully machined, with no obvious tool marks visible. They fit together very tightly, with any remaining slop taken up by a polymer wedge in the fire control group pocket. There are a host of little touches that scream attention to detail, such as a pair of replaceable roll pins that serve as engagement surfaces for the charging handle catch, or the steel insert that contacts the bolt’s cam pin to eliminate upper receiver wear. There’s even a replaceable steel insert pinned into the shell case deflector — useful to counter impacts from steel case heads. 

Controls are fully ambi, including bolt hold open, allowing the user to keep their hand on the pistol grip during stoppage drills. Southpaws are well taken care of, as in addition to the folding, non-reciprocating charging handle on the left of the upper, there’s an AR-style charging handle at the rear. In the civilian version, a two-stage, 4-pound trigger handles go-bang duties, while in the issued rifle, full auto is an option, courtesy of a three-position selector and auto sear. Sockets for QD sling swivels are present above the pistol grip, but no corresponding hardware exists on 

the handguards. Modularity in stock selection is provided by a 1913 rail milled into the rear of the lower receiver, and our test rifle arrived fitted with a folding AR-style adjustable stock, which locked up solidly. 

Finish-wise, SIG’s anodizers seem to have fully embraced the “50 shades of FDE” concept, as no component on the rifle matches the color of the one adjacent to it — including plastic parts, there are at least nine different hues present. Well played, guys, well played.

ROUNDS DOWNRANGE

After jamming the Spear’s metal magazine with 113-grain copper solids from the ammo can SIG thoughtfully sent along with their new baby, we headed to the range to get familiar with the rifle. Initial zeroing results were disappointing, as no matter how hard we concentrated, groups landed between 5 and 8 inches in spread. For grins, we loaded up a 12-gauge Mossberg 940 Pro with 1-ounce slugs and turned in a tighter, more consistent group than the Army’s new wunderwaffe. Rifling, who needs it? 

This was surprising, as every MCX we’ve shot has been a reliable, 1.5 MOA rifle — not quite as accurate as a good DI gun, but plenty good for its intended purpose. Other ammo options are somewhat limited, so we headed to the reloading bench and quickly worked up a load using Winchester StaBall 6.5 and 135-grain Sierra Matchkings. 

Forgive us for not sharing the specifics, but with no way to get pressure data, we’d be opening ourselves up to a world of hurt in this litigious landscape by printing it. Suffice to say, if you want to replicate it, look at cartridges with similar case capacities such as the 7mm-08 for a good place to start your journey, and when you hit the sweet spot, velocities will hover around 2,900 fps. 

The new loads all grouped less than 2 MOA, vindicating our experience of the MCX design. For whatever reason, the Army’s short range training round, despite screaming out of the 16-inch barrel at well over 3,200 fps, falls short when it comes to accuracy. We’ve heard that the service round itself is not exactly covering itself with glory either, and rumors abound of short barrel life when the gun is fed an exclusive diet of 80K psi service ammo. 

In terms of shooter experience, the rifle feels like a .308, with the same recoil and sensation of a scaled-up AR. The controls are just a bit stiffer, due to handling the bigger round, and split times when performing speed drills like Jason Falla’s Operator Readiness Test are noticeably slower. 

Should you buy one? If you’re a collector of U.S. Military firearms and have the coin, absolutely. The Spear in 6.8×51 marks a milestone in small arms development, even if it’s on the road to nowhere. Don’t get us wrong, it’ll be here for a while as programs like NGSW achieve their own momentum once they pass a certain development stage, but we’d be surprised if it gets fielded very widely, very quickly, and for very long for a number of reasons. 

The first obstacle to widespread employment is the need to establish a war stock of ammunition, while simultaneously training troops on the new system, burning rounds in the process. Before it can be fielded operationally, there needs to be a deep reserve of ammo — we’re talking tens of millions of rounds per division, and right now, that isn’t happening. SIG’s new ammo plant has yet to come online, though when it does, things might change.

With the issued suppressor and a loaded magazine, it’s quite the chonky boi. Add the Vortex optic the Army has selected and all-up weight tops 14 pounds. You read that correctly. Because its ammo is heavier, the basic load has been reduced to 140 rounds, from 210, and this downgraded amount is still 2.5 pounds heavier than the weapon it’s replacing. 

For those whose response might be, “You need to hit the gym more, we might point to the quality of recruits currently entering service, and how many we’re rejecting due to being soft, tubby, and weak in mind and body. For the record, I’m 195, bench 315 and would strongly prefer not to carry a boat anchor on an advance to contact, unless it’s belt-fed.

If you’re tempted to buy a Spear because it’s a good semi-auto rifle with an excellent feature set, then that’s a perfectly valid reason, but the .308 version is more appealing, particularly if you don’t reload — we would say to buy the model chambered in 6.5 Creed, but our sources at SIG say that following an initial run, that caliber isn’t going to be available for some time. 

Presently, there’s only one source for 277 Fury ammo, and as a consequence, your options are both limited and expensive. While we’re impressed by the level of detail that’s gone into the rifle, we’re less impressed with the Army’s decision-making process. 

SMALL ARMS AMMO SMORGASBORD

The U.S. Military small arms ammunition landscape is currently in a state of flux, and from the outside looking in, there appears to be a situation whereby the left hand doesn’t know what the right hand is doing or, if it does, thinks it can do it better. USSOCOM is currently casting around for vendors to convert their M240s to 6.5 Creedmoor, after selecting Geissele’s submission in this caliber for a mid-range gas gun for their snipers in 2023. 

DEVGRU guys are running around with small-frame ARs chambered in 6ARC, and there’s recently been a down selection in the long-running quest for a .338 Norma machine gun to supplant the venerable M2 Browning. Then, of course, the NGSW program guns have recently been fielded by the first units of big army. Those familiar with the long-running saga of U.S. small arms caliber selection will probably have difficulty performing any kind of meaningful task at the moment, as their eyeballs will be rotated permanently upward. 

Since before WWII, the entrenched establishment’s track record in this field is more than just a little bit, well, sh*t.

Look, 5.56 NATO isn’t great. But after five decades of refinement, it’s good enough. Likewise with 7.62×51. If we were starting with a clean sheet of paper, unencumbered by existing bolt face diameters and magazine dimensions constrained by established cartridge overall lengths, there’s no way anyone in their right mind would select these two cartridges as the ideal mainstays of an international alliance. 

But they’re what we currently have, and changing them will be a logistical nightmare. So, is there any way we can squeeze a bit more performance from them to tide us over, until phased plasma rifles in the 40-watt range come along? Glad you asked.

While the Army’s quest for a round specifically to defeat near-peer body armor might be moot, being able to poke holes in intermediate barriers isn’t a bad thing. And 5.56 isn’t very good at it. DSG ammo uses a tungsten penetrator wrapped in a short copper jacket to increase projectile mass and hardness, and we’ve personally shot their bullets through an MRAP armored window at 20 meters, from an 11.5-inch barreled AR. It’ll blow through a cinder block wall like it isn’t there, and defeat level IV plates out to 100 meters, again, from a shorty barrel. 

We’ve used an M134D minigun to push 7.62 projectiles through a 4-inch-thick reinforced concrete wall at 300 meters, and completely wreck sand-filled cinder blocks at 500 meters. It’ll punch ½-inch-thick A36 steel at 700 yards, too. If an updated projectile running at conventional pressures will match or exceed the performance of the NGSW ammo, is the juice from this multi-million-dollar taxpayer investment worth the squeeze? 

Or perhaps a better question might be, if we were to use SIG’s multi-part case to safely increase pressures, load it with DSG’s bullet, and team this with an updated barrel and bolt in existing M4 variants, can we get a cut of the resulting savings? By the way, our favorite color of Lambo is yellow, and thanks for listening to our TED talk.

SIG MCX-SPEAR .277 FURY	$4,200
SIG MCX-SPEAR .308 Win	$4,200
SIG MCX-SPEAR 6.5 Creedmoor	$4,200

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