Sig Sauer MCX-SPEAR Civilian Applications

Magic Prepper • January 15, 2025

The Sig Sauer MCX-SPEAR is a short-stroke gas piston driven rifle platform that is currently offered in 7.62x51mm NATO and the new 6.8x51mm to civilian shooters. It is the winner of the NGSW (Next Generation Squad Weapon) program and has been designated the XM7 by the US ARMY. The recent adoption of this weapon system by the US ARMY has generated a lot of interest in the civilian market, myself included, due to it possibly replacing the M4 carbine series of rifles. And as the AR-15 (civilian, semi-automatic version of the M4/M16 platforms) is the prepared citizen’s rifle of choice, the idea of it getting replaced in the military has many questioning if it would become similarly as popular as the AR-15 in the future.

And this is why I picked one up. Which has allowed me to get some trigger time in with this new system in order to develop an experienced opinion rather than relying on internet hearsay. I chose the 7.62x51mm NATO model as ammunition is more affordable, easier to acquire and plenty capable. It has the 13” barrel rather than the 16” because the XM7 chosen by the US ARMY also has a 13” barrel chambered in 6.8x51mm and I wanted to develop my opinions based on the same ergonomics and form factor. I am waiting on Sig Sauer to release the 13” 6.8x51mm conversion barrels to the civilian market to work with the new cartridge as well but I think we can all agree that 7.62x51mm NATO is currently a better all around ammunition type for your average American shooter. Now that I have had this rifle (yes, it is a form 1 SBR) for a year, I think I have a decent idea of what it can provide to a preparedness minded individual.

MCX-SPEAR Setup

First off, in order to build context and give you some ideas about how to set up the MCX-SPEAR, let’s go over the accessories I’ve tried and I’ve settled on (currently) that seem to work well with the rifle. The optic that the US ARMY has decided on is the XM157 made by Vortex. It’s a 1-8x LPVO with a built in electronics package that calculates ballistic data and provides the user with a HUD that helps to ensure first round on target hits. With that in mind, I started out with the Primary Arms PLXc Compact Rifle Scope which is also a 1-8x LPVO but does not have the technology package of the XM157. However, in concept it fits a similar form and function factor. I mounted it in a Primary Arms PLx Cantilever Picatinny-Style Mount with a PLx Top Cap Reflex Sight Mount that had a Trijicon RMR HRS Type 2 Reflex Red Dot Sight riding at 12 o’clock. Although this made sense at first and was inspired by the NGSW program’s decisions, I found it was lacking for me. The PLXc is an excellent optic, especially combined with the RMR on top but, I didn’t feel that I could take full advantage of the 7.62x51mm NATO with it. And as I was lacking the ballistic ranging technology provided by the XM157, I decided I wanted something that could reach out more with more consistency while considering my skill level.

Now, the MCX-SPEAR is already heavy for a modern fighting rifle coming in at 8.9 pounds unloaded. So weight needs to be a consideration which is why originally, I thought the lightweight PLXc LPVO was a good idea. But, with a requirement of more magnification, the durability expected from a fighting rifle optic and a limitation on weight, there was an obvious choice that was basically made for me. The Leupold Mark 5HD Rifle Scope fits the bill better than anything else in my opinion. I chose the 3.6-18x magnification range with the Horus Tremor 3 reticle (mostly because of my extremely windy environment) which even with a 35mm tube diameter, only weighs 26 ounces. Yes, that’s 9 ounces heavier than the PLXc 1-8x from Primary Arms but no other scope comes close to the glass clarity, durability and overall form factor of the Mark 5HD in that magnification range. Even the Nightforce NX8 2.5-20x weighs 28 ounces with a 30mm tube at the same 12 inch length. I mounted the Mark 5HD in the Leupold Mark Integral Mounting System (IMS) 1-Piece Picatinny-Style Mount and used the Leupold Mark 4 DeltaPoint Pro Top Ring Mount in conjunction with the KOENG ACRO Leupold Adapter + Spacer to mount an Aimpoint ACRO P-2 Red Dot Sight at 12 o’clock. This optics package allows me to shoot up close, at distance, under night vision and account for the awful wind I deal with here in North Dakota. All while instilling some faith in the overall durability of each individual component. It might not be the XM157 but it definitely serves my purposes quite well.

Another requirement of the NGSW program was the inclusion of a suppressor with the rifle. The Sig SLX Suppressor is standard issue with the XM7 and features a quick detach mount along with Low-Tox (low back pressure) technology. The sound and flash signature reduction provided by suppressors makes them an excellent addition to any modern fighting rifle. Especially when guns like the MCX-SPEAR come with a quick detach muzzle device and adjustable gas block from the factory meant to work with the Sig SLX Suppressor. Unfortunately, I don’t own a Sig SLX Suppressor and they are hard to get ahold of. So instead, I am using a HUXWRX Ventum 762 with a SilencerCo ASR 7.62 Flash Hider Suppressor Mount, Griffin Armament Tapered Shoulder Barrel Adapter and a SilencerCo Bravo ASR Mount for quick detach purposes. The HUXWRX Ventum 762 is also a flow-through, low back pressure design similar to the Sig SLX Suppressor so the performance should be similar. This way I am able to experience the rifle in the way that it was meant to be shot. This rifle was designed specifically to be suppressed which is apparent during testing. The recoil impulse and cyclic rate seem to be perfectly balanced when suppressed as opposed to unsuppressed. Keep this in mind whenever you see negative reviews about this platform as I often find they often involve the use of an unsuppressed MCX-SPEAR.

The remaining components are pretty straight forward. For the weapon light, I chose the Surefire Scout Light Pro IR Weapon Light with a Surefire DS-SR07 Weapon Light Tape Switch. This way I can switch to IR light if using night vision with my ACRO P-2 as an aiming solution. The rifle is already heavy and adding a LAM wasn’t going to work in my opinion. For a sling, I am using a Blue Force Gear Vickers Combat Applications Padded Two Point Rifle Sling with QD sling swivels. The padding on the sling helps with the weight and the MCX-SPEAR already has QD mounts integrated into the receiver and handguard.

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I also installed a Bravo Company (BCM) BCMGUNFIGHTER M-LOK Picatinny Rail Section at the front of the handguard in the 6 o’clock position for use with a QD bipod if needed. The stock I decided on is the Magpul Stock PR MOE Collapsible Carbine Stock. I ordered it before the “DT” version of the stock came out so I added a strip of hook and loop on the inside of the stock to eliminate rattle. I like this stock as it is lightweight and minimalist while offering some of the ergos usually found in precision rifle stocks. As for magazines, I have used both Magpul PMAG LR/SR Gen M3 Magazines and Lancer Systems L7 AWM Advanced Warfighter Magazines. Both magazines work perfectly and seem to hold up to being dropped while full of heavy 7.62x51mm cartridges (don’t ask how I know this). I am looking at testing out the Sig Sauer MCX-SPEAR Multi-Caliber Magazines as well since it was designed from the ground up for this rifle in particular.

So that’s how the rifle is currently set up. I went all out on this build as the rifle itself is already in the top tier category of expensive and cheaping out on the accessories just didn’t feel right. Not to mention, I wanted to get a well rounded experience out of this gun while having access to all of the modern “necessities” so that I could report back with the understanding that issues weren’t able to be blamed on poor gear selection. At this point I can say, if you want or have a MCX-SPEAR, this setup is definitely a strong contender for getting the full potential out of this gun. With that being said, what role does this gun actually fulfill? With this optics package you might be thinking DMR. But, I don’t think it would be the best option for that if accuracy was your priority. Having an IR capable light and top mounted NVG compatible red dot sight might make you consider it a battle rifle. But that could be more easily accomplished by a lightweight rifle package and a more simplistic optics setup like a red dot magnifier combo. So what role is this thing good for? Especially in a civilian context?

Small Arms Heavy Support

The more I shoot the MCX-SPEAR, the more my understanding of the rifle and its practical role in a civil defense capacity develops. Although I have achieved sub-moa 5 shot groups with this gun, it’s clearly not meant for long range precision. And even though it is set up for close range engagements if need be, it would never be my first choice if I knew for a fact that CQB was likely due to the increased weight and in tandem, decreased maneuverability. But that’s completely fine as it certainly can reach out accurately if needed. And it certainly can get through a room clearing endeavor when required. But where it really shines is not something I even considered initially when deciding to purchase the MCX-SPEAR. A role known as, “Small Arms Heavy Support” comes to mind.

To start, let's define what a small arms heavy support weapon is. It refers to a weapon that is considered a small arm due to its portability and individual use while providing significant firepower to support other team members. It can typically deliver sustained, heavy fire at longer ranges. This is usually reserved for light machine guns or automatic rifles with high capacity magazines. However, most civilians, myself included, don’t have access to fully automatic firearms. So a semi-automatic like the MCX-SPEAR will have to do. And do it will.

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There are a few reasons why this particular gun and its current setup has brought me to the small arms heavy support concept. One of those reasons is that it is capable of what might be referred to as accurate suppressive fire. This is a tactic that uses heavy, continuous fire that forces an enemy to remain in a defensive position. And as I have said before, this gun is capable of sub-moa accuracy and most definitely what most would consider to be combat accurate. Even with cheaper IMI M80 7.62x51mm NATO Ammo 150 Grain Full Metal Jacket it is still producing 2.25 MOA groups which is well within military standards of accuracy. Combined with an extremely capable optics package, the “accurate” part of accurate suppressive fire is definitely there.

As for the suppressive part, the short-stroke gas piston system on this rifle is much more ideal than a typical direct impingement system found on most AR-15 and AR-10 style rifles. It manages heat slightly better by keeping it away from the receiver and internal components. Since gasses are not being directly fed into the bolt carrier group, the shooter doesn’t get “gassed out” as easily while shooting suppressed. And with less gas in the system, you get less fouling which can keep things running more reliably for longer strings of fire. I have tested this myself and although you still get gas in your face eventually, it takes a much higher round count to achieve Snoop Dogg eyes than with direct impingement guns.

There are some other features the MCX-SPEAR provides that also lend themselves to this concept. For example, it comes standard with a SIG 2-Stage Matchlite Duo Trigger that makes fast, accurate shots easier to pull off. The adjustable gas block has two settings; Normal and Suppressed. So if the system starts to get hot and dirty as expected, you can switch over to “Normal” to increase the amount of gas pressure which in turn helps ensure reliable cycling. And the overall weight of the gun, which is relatively heavy, actually lends itself to this concept quite well. Absorbing the recoil amicably even though you’re spitting out 7.62mm projectiles at a high rate of fire.

A bipod becomes extremely useful and strapping a Harris Bipods S-LM Bipod to the piece of pic rail on the handguard with an American Defense MLOK Bipod Mount really enables accurate, sustained fire without fatiguing the shooter. I also include the Magpul PMAG D-50 LR/SR Gen M3 Drum Magazine as a must for this setup. 50 rounds of 7.62x51mm NATO that reliably feeds is hard to beat for this role. Speaking of 7.62x51mm NATO, in a small arms heavy support role, it far exceeds the capabilities of 5.56x45mm NATO. It is more accurate and delivers more energy on target at range. It can more easily overcome cover or barriers and is much more suitable for engaging vehicles. Since we are without full auto capabilities, the 7.62x51mm NATO cartridge helps make up for the rate of fire by meeting the “significant firepower” requirement of the small arms heavy support weapon role.

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Conclusion

Perhaps I made a solid case for the MCX-SPEAR to fulfill the role of small arms heavy support weapon in a civilian capacity. And maybe that isn’t something that most people would concern themselves with to begin with. But after spending a lot of time with this gun and trying to figure out what it does best, I believe I am at least in the ballpark of reasonability. Yes, the MCX-SPEAR is capable of any other role you want to shove it into. Want to take it deer hunting? Go for it. Need to stop a home invasion? Yup. Suddenly in need of sinking pirate speed boats off the port bow? Oh yeah. However, in the support role, it offers a lot of positive function while mitigating some of the negative drawbacks that seem to give people the most hesitation about the platform.

It’s definitely possible that the addition of the XM157 optical system and the 6.8x51mm cartridge could make the difference for the US ARMY’s plans of arming infantry units with the XM7. But for us civilians, the MCX-SPEAR seems like it fulfills a different need that we often overlook as it only applies to the worst of scenarios. With that in mind, if the worst of scenarios ever occurs, I’ll be pretty glad I can lend that level of support to the guys I have around me. And what a level of support it is. A small arms heavy level of support.

-- Magic Prepper

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