September 28, 2023

I’m a big fan of AKs and the 7.62x39mm cartridge in general – which is why the new SIG MCX-SPEAR LT Rifle had me really excited. As an AK-lover, I have a pretty decent stash of 7.62x39mm and have developed a love for the round. Plus, when I saw the new Spear LT being offered in my favorite caliber using its short-stroke piston operation with the gun’s excellent modularity, I thought I might have finally found the ultimate AK replacement. But after 800 rounds through the new Spear, I have a very different opinion on it.

SIG MCX-SPEAR LT Rifle – 7.62×39

Buy Now Gun DealsSee, the Spear LT in 7.62x39mm is the pre-2016 fedora-wearing Portland hipster of the AK alternatives; he scoffs at avarice and decadence while carrying a $6,000 MacBook paid for by his investment banker father because the Spear LT in 7.62x39mm takes the two most appealing aspects of owning an AK back in circa 2005 and throws them in the garbage – cheap rifles and cheap ammo – in favor of superior ergonomics and modularity.

SIG Spear LT Action
The Spear LT in 7.62x39mm is a very different beast than an AK. IMG Jim Grant

This isn’t to say the gun isn’t capable – it certainly is. Because the Spear can LARP with the rest of the AKs, blasting away 30-caliber rounds all day without a hiccup, but can swap out to more Western calibers with an Allen key, complete upper, and a checkbook.

The new SIG Spear LT is the latest iteration of the MCX carbine that the folks in Exeter, NH, have been churning out for the better part of a decade. The latest version – the Spear LT – is simply a lightened version with an ambi bolt release and an attractive FDE color scheme.

The Spear feeds from ASC STANAG-pattern 7.62x39mm magazines and includes a 28-round example in the box. These mags have been notoriously unreliable in the past, but I never encountered a magazine-related failure in all my testing. On a side note, if you’re going to be shooting from a prone position or even from a bench, invest in some of the 20-round versions, as they are vastly more compact.

Spear LT 20-round magazine
The Spear is much more compact with a 20-round magazine than the included 28-round version. IMG Jim Grant

For those of you not familiar with the SIG MCX-SPEAR LT Rifle, it was SIG’s answer to military demands for a more reliable weapon than the aging M4. While only the integrally-suppressed version saw US military adoption, many police departments and civilian shooters alike have found the guns to be excellent. And these experiences have mirrored my own with the 5.56mm and .300blk versions at least – but the 7.62x39mm is a different story.


During the course of my time with the Spear LT, I fired 800 rounds of Tula, Wolf, Barnaul, and Belom ammo through the gun. During that time, the only issues with reliability I encountered were with a suppressor attached.

All of these issues stem from the gun being over-gassed with a can installed. Yes, the Spear LT has an adjustable gas valve, but it only has two positions – normal and adverse. According to the manual, I should keep the gas valve in the ‘standard’ position for suppressed use. But in my experience, this caused failures to feed roughly 10% of the time. And just for the record, every one of these failures caused the round to nose-dive into the feed ramp, setting the bullet too far into the case to be safe to shoot.

Spear LT Handguard
The Spear LT’s handguard hides the adjustable gas valve underneath it. IMG Jim Grant

Without a suppressor installed, the Spear LT in 7.62x39mm ran flawlessly. But there are a few other issues I want to mention.

The first and biggest to me personally is the felt recoil. I’ve shot dozens of AK rifles tens of thousands of times, and with the exception of a Draco, none of them have as much recoil as the Spear. Which is really odd if you think about the physics involved. AKs are long-stroke piston-driven rifles and, as such, have a massive reciprocating bolt carrier group that chugs back and forth with every trigger pull. This translates into stout felt recoil.

Russia addressed this by changing the gas block to 90 degrees and installing a massive two-port comp on the end of the barrel. (The 90-degree gas block reduces recoil over time since the 45-degree AKM gas blocks tend to open up with extended use and cause the gun to become ever more over-gassed than normal.)

The Spear, on the other hand, uses a short-stroke piston system which, in the simplest terms, means that the piston isn’t attached to the bolt carrier and thus reduces the weight (and felt recoil) of the reciprocating mass inside the gun. Despite this, the SIG MCX-SPEAR LT Rifle kicks more like a .308 HK G3 rifle than an intermediate-caliber carbine.

Spear LT Flash Hider
The Spear ships with a three-prong flash-hider that does little to reduce felt recoil. Thankfully the barrel is threaded to 5/8×24, so shooters can install any 30-caliber brake they want. IMG Jim Grant

If you’re scratching your head and wondering how the hell that’s even possible, there’s really only one explanation – gas. The 7.62x39mm Spear LT is simply over-gassed. I completely understand why, though. The engineers at SIG didn’t want someone using the cheapest AK ammo possible and having malfunctions due to low-power ammo.

A better, albeit more expensive, solution would be to have a three-position gas valve with a low, standard, and high setting. I assume the reasons SIG didn’t go with this solution are the cost and logistics of adding another caliber-specific component to production.

Spear Action
While it’s possible to shoot quickly with the Spear, the felt recoil makes rapid hits tough. IMG Jim Grant

Accuracy, Barrel Flex, and the Internet

Don’t worry, I’m getting to the elephant in the room in a second. But first, I want to talk about the gun’s accuracy. With standard steel-cased Soviet ammo, the Spear LT in 7.62x39mm regularly produced groups hovering around 2.3 MOA. When I fed it the brass-cased ‘good stuff’ from Belom and Norma, these groups shrunk to an incredible 1.3 MOA!

This just goes to show that with a proper rifle, the 7.62x39mm round is capable of very good accuracy. But what about the whole barrel flex issue?

Alright, if you’re not familiar, some users on the internet have reported that they could cause either the barrel or handguard to shift if they squeezed the two together with their hands. And they’re not wrong; this is 100% true. It’s also true that unless you’re running a laser sight or irons, this doesn’t really matter.

Spear LT Barrel Flex
The so-called barrel flex of the Spear is total nonsense and is vastly overblown by know-nothing internet experts. IMG Jim Grant

Because in my experience, the barrel doesn’t actually shift when squeezed, merely its position relative to the handguards – suggesting that the handguard itself moves, not the barrel. I tested two magazines worth of ammo, shifting the handguards as hard as I could (without tools) and shooting groups to see if this caused a wondering zero issue – and it didn’t. It also didn’t measurably affect accuracy.

Yes, I saw the posts online of people pressing the Spear LT’s handguards against a wall and shooting groups and having accuracy issues. If this surprises you, congratulations on your first gun. All guns have issues with consistent groupings if you drastically alter the barrel’s harmonics between shots. This is the whole reason that free-floating a barrel is such a big deal when it comes to accuracy.

Spear LT suppressed
The Spear proved capable of incredible accuracy. IMG Jim Grant

Does this mean that I think it’s a total nothing-burger? No. The gun should be more rugged than it is, but it’s not the smoking gun every ‘internet expert’ claims it is. Plus, check our favorite AR-15 – the handguards do the same thing unless you have an LMT with a monolithic upper.

And if the issue keeps you up at night, the fine folks over at Arisaka Defense make a barrel clamp replacement that totally solves the issue for $50.

Spear LT Grip
The Spear’s grip. IMG Jim Grant

7.62x39mm SIG MCX-SPEAR LT Rifle Verdict

With an MSRP of nearly $2,500, the SIG MCX-SPEAR LT is not a cheap gun. It’s also not the AK-killer that I personally hoped it would be. But I can’t jump on the hate train against it, either. The SIG MCX-SPEAR LT Rifle in 7.62x39mm is an interesting take on the MCX carbine chambered in a cool round that still isn’t incredibly expensive and makes a great hog-slaying tool. As it stands, the Spear LT is a far cry from a replacement for my AKs or even my Galil Ace in 7.62x39mm. But if the gun had a third gas setting and fed from AK magazines, I would literally sell some of my AKs to buy it.

Spear LT Stock
The Spear ships with a folding stock, but shooters can install whatever they want with a proper adaptor. IMG Jim Grant

SIG MCX-SPEAR LT Rifle Specifications:

  • Model Name: SIG MCX-SPEAR LT Rifle
  • MPN: RMCX-762R-16B-LT
  • Brand: Sig Sauer
  • UPC: 798681660889
  • MSRP: $2500.00
  • Caliber: 7.62×39
  • Barrel Length: 16 in [406.4 mm]
  • Mags Included: (1) 28rd Steel Mag
  • Mag Type: AR-15 [7.62X39]
  • Action Type: Semi-Auto
  • Stock Type: Folding
  • Barrel Material: Carbon Steel
  • Trigger Type: Flat Blade Match
  • Twist Rate: 1:9.5
  • Forend Type: Alloy
  • Grip Type: Polymer
  • Receiver Finish: Coyote
  • Overall Length: 34.5 in [876.3 mm]
  • Overall Width: 2.9 in [73.7 mm]
  • Heights: 7.5 in [190.5 mm] without magazine
  • Threads: 5/8 in – 24
  • Accessory Rail: M-LOK
  • Operating System: Gas Piston
  • Weight: 7.6 lb (3.5 kg)

SIG MCX-SPEAR LT Rifle Owners Manual

About Jim Grant

Jim is one of the elite editors for, who in addition to his mastery of prose, can wield a camera with expert finesse. He loves anything and everything guns but holds firearms from the Cold War in a special place in his heart.

When he’s not reviewing guns or shooting for fun and competition, Jim can be found hiking and hunting with his wife Kimberly, their son, and their dog Peanut in the South Carolina low country.

Jim Grant

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