Sig Sauer MCX Spear LT Review: Evolution of the AR-15 Style Platform?

by coldboremiracle

January 5, 2024



Sig Sauer is perhaps one of the biggest names in the weapons industry. They have released one successful product after another, and today we bring you another one. The MCX has been a popular rifle platform for years, and today we are reviewing the latest generation of the MCX family; the MCX Spear LT.

Sig Sauer MCX Spear LT Specs

  • Caliber 5.56 Nato
  • Action Semi-auto
  • Capacity 30
  • Operating System Gas piston
  • Barrel Length 11 in
  • Barrel Twist 1:7
  • Muzzle Threads 1/2-28TPI
  • Overall Length 29.5 in
  • Weight 6.9 lbs

Sig Sauer MCX Background 

The MCX is a relatively recent firearm family. It was designed to change up what we consider standard AR-15 operation. By removing the buffer-tube from the back of the receiver, engineers made it possible to fold or remove the buttstock of the MCX without affecting its ability to fire. And by adding a gas piston operating system, they aimed to increase reliability and durability. 

The buffering system wasn’t just removed, it instead migrated into the upper receiver. Using two captured recoil springs that ride above the bolt carrier allows the MCX to ditch the traditional buffer-tube and any issues that come with it. 

The MCX Spear is the latest version of the MCX, which brings additional design enhancements.

Sig Sauer MCX Spear LT Features

Sig Sauer MCX Spear LT Features
1 Internal Buffer system

By migrating the buffer system into the upper receiver, we can fire the rifle without a stock, or with the stock folded.

2 Ambidextrous Controls

With all controls featured on both sides of the rifle, you can’t be wrong-handed.

3 Gas Piston Operating System

Using a gas piston reduces fouling by keeping gas flow out of the upper receiver. And increases reliability with multiple gas settings.

4 Interchangeable Barrel System

The barrel block in the upper receiver allows users to remove the barrel and swap for different calibers with minimal tools.

5 M-Lok Handguard

For adding all your favorite accessories to the front of the rifle.

6 Threaded Muzzle

With ½-28 threads on the muzzle, you can add your favorite suppressor or other muzzle device. Be careful though it’s on there TIGHT.

Models and Variations of the Sig Sauer MCX Spear

The Sig Sauer MCX Spear is available in several configurations. There are pistol models that come without a buttstock in both nine-inch and eleven-inch barrel lengths. We can have these in either 5.56 Nato or 7.62×39 with eleven-inch barrels, or 300Blk with nine-inch barrels. SBR versions are also available with a buttstock.

The full size rifle is also available with a sixteen-inch 5.56 or 7.62×39 barrel. As well as the big boy version chambered in 7.62×51 NATO

Sig Sauer MCX Spear LT Review

Sig Sauer MCX Spear LT Hero

Testing the MCX Spear LT would take me to the high desert. Before leaving, I grabbed a few hundred rounds of PMC Bronze 5.56 ammunition. I’d also added a US Optics red dot sight to use together with the rifle. 

Being that the Spear LT is a Short Barreled Rifle (SBR) I wasn’t too worried about its performance at any extended ranges. SBRs are for use in up close situations, most likely inside three to four-hundred yards. And for that, the red dot would do fine.

I fired a few rounds to confirm a good zero before transitioning to a variety of targets from 30 to 150 yards. With roughly an 80 yard zero, it was easy to hit most everything in that range without having to change my hold. I went through several magazines that way, shooting from one target to another, varying shooting positions between shots. 


The flat-shoe trigger on the Spear felt crisp and predictable every time. It’s certainly not a match trigger or anything like that, but very serviceable for a fighting rifle. The short length of the rifle made it very easy to maneuver around and present on targets. In addition, its light weight made the rifle easy to hold up and keep on target. 

The controls of the rifle are outstanding, making reloads very quick. I really appreciated the ambidextrous bolt-release, especially when it came to mag changes. The minimalist folding stock was just enough to support the rifle properly while shooting. 


Having shot this rifle for several months now, I can tell you it loves to run. I have experienced zero malfunctions while shooting the rifle. There is the occasional problem when you don’t fully stroke the charging handle, but that’s not an MCX Spear issue.

Shooting the rifle with a suppressor or the factory muzzle device proved to work great. With the YHM Turbo suppressor and the gas valve turned down, you experience maximum control of the rifle. We also shot with the Huxwrx Flow 556 suppressor, which ran great on the standard setting. 


It’s hard to complain much about AR type rifle ergonomics and the MCX Spear is no different.

The grip that comes with the rifle is particularly comfy in my opinion, but that is, of course, just mine. You can swap it for the one you prefer.

The bare handguard can be a touch cold in the winter months. I wouldn’t mind adding a down-grip or some other device to the handguard, but again, that’s just my preference. At the rear of the rifle, the buttstock is pretty simplistic. I don’t mind it at all, but depending on the sights you install on the rifle, you might want something to rest your cheek on. 

I’ll again mention that the ambi controls are fantastic, should you find yourself in left-handed company. 


To better test the accuracy of the Spear, I installed a SAI 1-6 rifle scope. While not exactly a precision rifle, I figured a 6x scope would be much better suited for testing the rifle’s accuracy.

This time, with a target hung at 100 yards, I fired a couple of five shot groups using the PMC Bronze ammunition. In a surprise to no one, groups averaged around 1-2 MOA. 

No doubt that if I had a slightly better scope, and shot some match grade ammunition, this rifle would do even better. Probably MOA or better.


With an MSRP of $2499.00, the Spear is not an impulse buy for most of us. But to be fair, this rifle isn’t exactly marketed towards the folks that like to plink at milk jugs once a month, either. They market the MCS Spear LT as a fighting rifle suitable for any instance you might need. With both military and law enforcement applications being very likely, the price isn’t a surprise. 

With comparable rifles fetching similar prices, I cannot fault Sig for pricing the Spear LT so high. It’s certainly more money and rifle than the average gun owner will probably need. But this is America, and don’t let anybody tell you what you need or don’t. If you demand excellence, then go for the gold…or…Coyote I guess Sig calls it. 

Final Thoughts on the MCX Spear LT

The Sig Sauer MCX Spear LT is a fantastic rifle. It brings Sig’s renowned quality and performance together with innovative design. The rifle feels like it was designed to be ridden hard, and it certainly stands up to it. The performance was reliable and particularly pleasant, mainly due to its soft recoil, light weight, and muzzle neutrality. 

The controls added to the experience, making the hits even more satisfying. I feel that regardless of your shooting discipline or purpose, the Sig Sauer MCX Spear LT will certainly fill the role well. 

Sig Sauer MCX Spear LT Pros and Cons 

  • Excellent reliability
  • Outstanding fit and finish
  • Great trigger
  • M-Lok compatible
  • Folding stock
  • No buffer tube
  • Adjustable gas system
  • Piston operation
  • Ambi controls
  • Multi-caliber
  • Muzzle brake was glued on like a MF
  • Not inexpensive
  • SBR forces you to negotiate with Federal thieves

Report Card


The MCX Spear LT was an absolute joy to shoot. They made everything about it to run quick and smooth.


We didn’t experience any real malfunctions while shooting.


Good grip angles and modular handguard design allow the rifle to be comfortable for anyone.


For a rifle of this type, the MCX Spear LT shot as predicted, and reliably


Only because you can get similar rifles for less that perform comparably. But they aren’t an MCX.

Sig Sauer MCX Spear LT Final Grade

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Sig Sauer MCX Spear LT Range Pack

Here are some items we think you will want when you take your Sig Sauer MCX Spear LT to the range:

  • Eye Protection: In our best shooting glasses article you will find a good pair of eye protection for your shooting needs.
  • Hearing Protection: You wont want to go to the range without some good hearing protection.
  • Gun Cleaning Kit: A good gun cleaning kit will make maintenance easier.
  • First Aid Kit – A good first aid kit is something you will want to have with you, not just for range trips.

Sig Sauer MCX Spear LT Gun Deals

Upgrades and Accessories for the Sig Sauer MCX Spear LT


The Spear LT is well deserving of a good suppressor. If you aren’t going to buy the Sig Sauer suppressors designed for the Spear, I’d recommend the Dead Air Sandman S or K model. It’s easy on, and easy off. And provides significant noise reduction (the S more than the K). The suppressors shown here are also excellent choices.

A Good Sling

A good sling is a must have for a fighting rifle. A good choice for this rifle would be the Vickers sling from Blue Force Gear. Whether you are transitioning to your pistol or grabbing a pizza, it allows rapid adjustment for shooting on the go. 

Sight Options

I am a big fan of LPVOs, I really like the SAI 1-6 power rifle scope for this gun. Another excellent choice would be the Sig Sauer Tango 6T. Either of them provides excellent performance and quality that matches the MCX Spear LT. 

I’d also say that it could use some good BUIS as well. There are so many great options out there, I’d recommend a set from Ultradyne 

Upgrades and Accessories for the Sig Sauer MCX Spear LT

Deadair Sandmand K 7.62
  • Can change the cap to .223 or .30 caliber
  • Quick detach KeyMo system
  • No barrel length restrictions
  • Safe up to .300 RUM
Check Price
Blue Force Gear Vickers Tactical sling
  • Quick adjustment slide
  • Several color options
  • Used by the military
Buy on Amazon
Sig TANGO6T 1-6x24
  • 1-6x magnification range
  • First focal plane
  • Illuminated reticle with night vision settings
Buy on Amazon
Ultradyne C2 Folding Front and Rear Sight Combo
  • Metal flip up sights
  • Quick deployment
Check Price

Ammo for the Sig Sauer MCX Spear LT

For the most of my shooting, we used PMC Bronze 55 grain FMJ ammunition. We also shot a few boxes of American Eagle XM 55 grain ammunition. Both of them worked great and had similar accuracy results. 

For defense, I would likely use Speer Gold Dot 75 grain ammunition, if you can find it. It cycles great through all my firearms and brings a defensive edge to targets.

Range Rounds

PMC Bronze 223 55 Grain

PMC Bronze 55 Gr FMJ

Cost Per Round
Gun Deals $0.44
Firearms Depot $0.49 $0.54
Sportsman’s Guide $0.59

Self Defense Rounds

Speer Gold Dot 75 Gr

Speer Gold Dot 75 Gr

Cost Per Round
Gun Deals $1.15
Brownells $1.35
Optics Planet $1.75

Other Rifles of its Class to Check Out

If you are looking to stay in the typical AR-15 operating system, check out our best AR-15 list.

If you like the idea of AR-15 ergonomics but with a different operating system that eliminates the buffer tube, check out the CMMG Dissent.

And, if you want a full length barrel, but in a smaller form factor, maybe a bullpup is right for you. Check out the Tavor X95, it is a favorite around here.

1 CMMG Dissent 300BLK

CMMG Dissent 300 BLK

CMMG Dissent 300BLK

The Dissent is an AR anomaly that uses a proprietary compact action instead of the typical buffer system.

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2 IWI Tavor X95

IWI Tavor X95

The Tavor X95 has by far earned the Best Overall Bullpup Award. You can see below why we made that decision.

Check Latest Price

  • Shootability A+
  • Reliability A+
  • Ergonomics A+
  • Accuracy A+
  • Value A

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How to Care for Your Sig Sauer MCX Spear LT

This video will show you how to disassemble your MCX Spear LT for maintenance.

Here are some links to the manufacturers website and user manual.


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About coldboremiracle

coldboremiracle is a self-taught "Freelance Sharpshooter" based in the Rocky Mountains. A true gun nut at heart, but has a passion for precision shooting particularly as it applies to hunting. When not at home or work, he is more than likely behind a riflescope in the high country evaluating the wind for the next shot.

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