Custom SIG Sauer MCX Virtus
• Based on SIG Sauer MCX Virtus
• Outfitted for night vision/low-light use
• Chambered in 5.56x45mm
In April 2022, the U.S. Army selected the SIG Sauer XM7 as the replacement for the venerable M4 carbine, a weapon that has been the main armament for American infantry units for well over four decades. The all-new XM7 rifle is chambered for the 6.8×51mm SIG Fury cartridge and promises to change the capabilities of the soldier on the battlefield.
As a military firearms enthusiast, Mike M. was intrigued by the Army’s choice. Like many of us, Mike’s an AR fan and has made clones of several military-style rifles including an M4A1, Mk 18 and a Mk 12 SPR.
“As silly as it sounds, I was torn at the prospect of seeing the AR platform outdated, so to speak,” he tells us. “It’s nice knowing that similar firearms to my own are currently being fielded by the military. When it completely switches over to the XM7, the AR types in my collection will end up being yesterday’s news.” We get what he’s saying; much like the retired M1 Garand and M14, seeing a legend like the M4 discharged from the service is going to take some getting used to.
The good news for Mike was that the XM7 is based on the SIG MCX, a couple of which he already owns. “I’m a fan of the MCX,” he says. “It’s a modern rifle that comes in many different variants. I haven’t purchased an MCX-Spear [the civilian version of the XM7] yet, but since I’m a military clone guy, it’ll be next on my list.”
Since the news of the XM7’s adoption broke, Mike reexamined his MCXs and decided to start shooting them more. As mentioned, he’s primarily an AR guy so that’s what he regularly reaches for when heading to the range. That said, he does have an MCX Virtus Patrol that he occasionally takes target shooting.
With the XM7 serving as inspiration, he decided that he needed to take it out to the range more often and perhaps to a tactical class to see how he handles it in a more active environment—and that he did. As he shot it more, he quickly realized that there were modifications he wanted to make to the factory-stock Virtus.
“My Virtus came chambered for 300 BLK, which as you can imagine is simultaneously fun and expensive to shoot,” he goes on to say. “I didn’t mind it so much when it was one of my novelty rifles, only going through a mag at most during a trip to the range, but since I’ve decided to get more familiar with shooting the MCX, I swapped out the 300 BLK barrel with one made for 5.56 NATO. Swapping out barrels was as easy as loosening a couple of bolts; SIG makes it easy. Within seconds, I can have it back in 300 BLK configuration, and that’s one of the great things about the MCX platform.”
After changing it to 5.56x45mm, Mike started putting plenty of rounds through it. During the course of his MCX familiarization, he realized that there were a few more upgrades that he wanted to add to it. And naturally, those “few” upgrades ended up being only the beginning of a whole host.
To make the handguard grippier and less hot to handle, he added RailScales HTP Scales handguard covers in both Honeycomb and MiniDot textures. These m-lok compatible plastic rail panels help to add grip and keep bare hands shielded from the heat that soaks into the handguard. Slung underneath the handguard is a JMac Customs HRD handstop, finished in a tan anodized color that JMac calls “Tanodized.” We like its look.
It is said that the MCX’s handguard can flex when force is applied to it, degrading the rifle’s accuracy. To remedy this, Mike installed an Arisaka MCX Zero Retention Clamp. The ZRC keeps the handguard from flexing, avoiding a laser or front sight zero change when pressure is applied to the guard.
Staying on the front end of the rifle, you’ll notice a SureFire Warden attached to the barrel. The blast regulator is engineered to direct concussive blasts forward without venting gases to the sides. This aids in reducing the overpressure felt by others at either side of the shooter’s firing position. Mike’s friends and shooting classmates are sure to appreciate that.
Moving to the MCX’s lower receiver, you’ll notice that Mike installed an upgraded RailScales MCX CSMR magazine release button. It’s made of aluminum and finished in anodized tan, and Mike admits he got it mainly for its bling factor. What he didn’t add just for bling is a Geissele Automatics Super MCX SSA M4 curved trigger.
The high performance Super MCX SSA was designed as a combat-inspired two-stage trigger. The Super MCX delivers all of the enhanced performance, reliability and safety that shooters expect from an upgraded trigger. The two-stage trigger is rated at about 4.5 pounds of pull and is non-adjustable. Mike tells us it’s one of his favorite upgrades.
Inspired by one of Chip Lasky’s articles in a previous UN12, he also ordered up and installed an HRF Concepts MCX Rifle Combat Magwell. This magwell swallows up magazines and funnels them into the receiver for quicker reloads. The lower is completed with a Radian Talon ambidextrous safety selector and Strike Industries Ultralight pivot and takedown pins.
Moving to the upper receiver, we spotted a Strike Industries Ultimate Dust Cover and Rainier Arms Avalanche SIG MCX ambidextrous charging handle. Regarding these two upgrades, Mike says: “The Strike dust cover looks cool, but due to its thicker profile it doesn’t flip as far down as the factory stamped steel cover does. It hasn’t caused any malfunctions even after a few thousand rounds, but I’m keeping my eye on it. The Rainier Arms Avalanche ambi handle is a nice piece that I’m glad I added.”
The rear end of the MCX Virtus sees some really neat buttstock upgrades. The standard stock was changed out for a sexier JMac Customs SS-8R Skeleton Stock finished the brand’s Tanodized color just like the handstop up front. The stock is fitted to a folding Picatinny rail adapter that comes with the unit. The MCX has a tall profile, so to get his cheek in the right place Mike added a KM3 Solutions Cantilever Cheek Riser to the stock. The cheek riser positions him perfectly to put his eyes in the EOTech optic’s line of sight.
Speaking of optics, let’s delve into this MCX’s sighting setup. First up is the EOTech EXPS3 holographic sight that rides on top of a Unity Tactical FAST Optic Riser. The familiar ringed EOTech reticle is a favorite of Mike’s and he has the brand’s optics on most of his rifles. He’s been trying out the heads-up shooting stance thanks to Unity Tactical’s riser.
Unity’s FAST riser securely elevates optics with a standard lower 1/3 co-witness Picatinny mount to a 2.26-inch optical center line. The raised position allows shooters to shoot heads-up as opposed to tucked down low behind a lower-riding optic. Some advantages of heads-up shooting include less neck strain and better situational awareness, not to mention easier use when donning a helmet-mounted night vision device.
Backing up the EOTech is a Midwest Industries Combat Rifle rear flip sight and a RailScales PEQ-LEAF fixed iron sight in the front. Tucked right behind the PEQ-LEAF front sight is an EOTech commercial ATPIAL (Advanced Target Pointer/Illuminator/Aiming Laser). The ATPIAL-C is a civilian version of the U.S. Army’s AN/PEQ-15 laser unit and allows for visible and infrared (IR) laser targeting.
To operate the laser, Mike opted to use a Unity Tactical TAPS (Tactical Augmented Pressure Switch). Co-developed by TNVC and Unity Tactical, the TAPS is a complete single-point command and control system that provides low-profile, dual-device control for lights and lasers. The MCX is also outfitted with a SureFire Mini Scout Light Pro infrared weaponlight that allows Mike to light up targets in white or IR light.
With lights and lasers come wires. To keep things tidy and to reduce chances of snagging, you’ll notice that Mike installed a Strike Industries Multidirectional Picatinny Rail Cover just aft of the TAPS and a trio of Emissary Development micro cable clips on the right side of the handguard. The light, laser and activation switch setup looks clean and we like how the wires are up against the rail nice and tight. It’s a pretty tidy package he’s got going on.
Mike reports that he’s gotten loads more comfortable using his fully outfitted MCX Virtus at the range. He’s only done a couple of tactical classes with it, but he’s liking it so far. Will it replace his ARs as his main go-to rifle? That still remains to be seen. In the meantime, now that he’s gotten his MCX up to speed, he will be using it more often. That is, of course, until he eventually gets hold of a SIG MCX-Spear.
Build Sheet – Custom SIG Sauer – MCX Virtus
Specifications
Base Rifle: SIG Sauer MCX Virtus
Caliber: 5.56x45mm & 300 BLK
Capacity: 30 +1
Max. Length: 35.5 in.
Barrel Length: 16 in.
Coatings: SIG Sauer FDE Cerakote
Featured Accessories
Optic: EOTech EXPS3
Optic Mount: Unity Tactical FAST Optic Riser
Handguard: Midwest Industries 15” MCX Virtus Handguard Custom Cerakoted in FDE by Rifle Supply
Laser: EOTech Commercial ATPIAL
Weaponlight: SureFire Mini Scout Light Pro Infrared
Parts & Accessories: SureFire Warden, RailScales HTP Scales, Arisaka MCX Zero Retention Clamp, RailScales MCX CSMR button, HRF Concepts MCX Rifle Combat Magwell, Geissele Automatics Super MCX SSA M4 curved trigger, Radian Talon ambidextrous safety selector, Strike Industries Ultralight pivot/takedown pins, Rainier Arms Avalanche SIG MCX ambidextrous charging handle, Strike Industries Ultimate Dust Cover, JMac Customs SS-8R Skeleton Stock w/ 1913 Folder “Tanodized”, JMac Customs HRD handstop “Tanodized”, KM3 Solutions cantilever cheek riser, RailScales PEQ-LEAF fixed iron sight, Midwest Industries Combat Rifle rear flip sight, Strike Industries Multidirectional Picatinny rail cover with cable management, Emissary Development micro cable clip, SureFire UE tailcap, Unity Tactical TAPS V3
