Definitive Guide to the Sig MCX | Why Do I Use the PDW Brace?

The Sig MCX platform has 7 distinct guns that carry unique features, capabilities, and, unfortunately, legal concerns. We’ll do our best to keep you updated on any new laws that pass, regarding AR-pistol braces and SBRs, but for now, we’re excited to share our thoughts on the PDW brace from Maxim Defense.

Not only will you have a complete understanding of the Sig Sauer MCX line of guns, but also which guns are perfect for the Maxim Defense PDW Brace. 

Installing a brace for added stabilization is a brilliant choice for anyone trying to optimize their PDWs. Maxim Defense has uniquely fitted the PDW Brace with any Sig MCX to provide versatility, improved performance, and durability that’s hard to match.

Regardless of which Sig MCX you have, the PDW Brace fits perfectly with the help of a bench gun vice grip and armorer’s wrench. 

What is a Pistol Brace?

A pistol brace has very distinctive features that, once you know, you’ll never forget. For starters, if it’s classified as an SBR or AR-pistol brace, it has to have a hole to fit your arm through, with an adjustable strap to tighten for added stability. A pistol brace will attach to your forearm to provide the stability of absorbing the felt-recoil of a 5.56 NATO bullet. Pistol braces are shot with one hand but can be legally shouldered without forcing yourself to get a federal tax stamp for the brace. 

What is an SBR?

A Short Barrel Rifle (SBR) is a gun with a barrel of less than 16" and an overall length of less than 26", but also meant for use as a rifle. For example, an AR-pistol would be an SBR without a shoulder stock and designed to be fired with one hand like a pistol. The way you can avoid getting into trouble with the ATF is to have a pistol brace with an opening for your arm and a strap for securing your forearm to the weapon platform. As long as you can prove that your MCX SBR is meant for single-arm fire, you can shoulder it without having to register with the NFA.

Why Would You Need A Pistol/SBR Brace?

A pistol brace is to help shooters control high-powered gun calibers, like the 5.56 NATO, .300 BLK, 6.5 Creedmoor, and a new caliber like the .277 FURY(6.8x51mm) in a shorter platform. If you’re following along with the ATF, they classify an SBR as having a barrel length of less than 16". Our advancements in engineering have given us guns that have assault rifle capabilities but are on sub-compact platforms. 

For all the veteran shooters out there, you know, with a shorter barrel and higher caliber; the recoil is going to be felt in your bones and your muzzle will flip like a gymnast. A pistol brace takes the place of a traditional shoulder stock and allows the shooter to stabilize the gun with one arm. 

So, to make things a little simpler, an AR pistol brace has a hole in it and typically has a Velcro strap that’s intended to wrap around the arm. A pistol brace doesn’t actually have to be velcroed to your arm though, it just has to work as a brace, meaning it can sit against your arm providing an additional point of contact to stabilize the firearm.

As far as the legality of it all, an SBR is shoulder-fired with both hands on the gun. A brace is there to support your arm while you fire with one hand, therefore, a brace won’t affect the legality of the gun if it’s longer than 26" and designed to be shoulder-fired. There are obviously a lot of insinuations in the ATF laws, that’s why they’re changing the law. 

What type of gun is the SIG MCX?

There are currently 7 Sig MCX guns in production, with varying purposes and features to fit any mission type. Before we get into the aftermarket weapon upgrades, I think it’s vital to understand each weapon platform and how they’re different. I’ve only shot the Sig Rattler SBR and the Sig MCX Virtus SBR, so this won’t be as much of a review as it is an educational blog to help you understand the purpose of each Sig MCX model. 

Why Should I Choose the Sig MCX Rattler Canebrake?

I would choose the Canebrake if I were looking for a CQB gun that will give me the firepower needed to take on multiple assailants, but also provide modularity for customization. Sig specifically designed the MCX Rattler Canebrake as an AR-pistol. The whole point of this gun was to run a suppressor for clandestine military operations where stealth and fire superiority are a must. 

The Sig inert training device at the muzzle of the barrel provides the shooter the ability to attach any 7.62mm suppressor, with no additional tools or components. This is important because, for as much money as this gun costs, buying an additional threaded barrel or adaptors can add up quickly. You’ll need an NFA tax stamp for the CaneBrake, but once that’s done, you can attach a suppressor free from hassle from the government. 

Sig MCX Rattler Canebrake

$3,049.00

at Guns.com

VIEW DETAILS

Prices accurate at time of writing

Why Should I Choose the Sig MCX Virtus Patrol Rifle?

The MCX Virtus Patrol rifle is one that I would have given a finger to use over my M4, during OIF. For gun owners, it’s incredible because it’s not an SBR or AR-pistol, therefore, you won’t need a tax stamp. The 16" carbon steel barrel dissipates heat better than stainless steel and will last years longer than a traditional steel barrel. This rifle is perfect for a long gun to use for intermediate and CQB targets. 

Sig has always been one of the most revolutionary gun manufacturers, with pistols and rifles used by militaries around the world. The Virtus Patrol rifle is perfect for infantry soldiers, and police officers, who need an effective full-size rifle for combat operations. 

Why Should I Choose the Sig MCX Rattler SBR?

The MCX Rattler SBR is my favorite and the choice I’d make if I were looking for an SBR. Not only does the gun come in both .300 Blackout and 5.56 NATO, but it’s also 6" shorter than the CaneBrake and almost a full pound lighter if you choose the .300 BLK platform. My only complaint about the MCX Rattler is the minimalist stock because it doesn’t seem to help much with the felt recoil. 

Adding an after-market stock to the MCX Rattler will enhance the capability and performance of the gun. The original Rattler SBR is also $500-$600 cheaper than the CaneBrake and offers the same capacity. The only differences that make the CaneBrake more expensive are the barrel finish, stock, and FDE finish to the gun. Regardless, the Matchlite trigger system inside the 5.56 NATO Rattler provides one of the smoothest breaking triggers I’ve shot with, outside of a bolt-action rifle. 

Why Should I Choose The Sig MCX Virtus SBR?

The Virtus SBR is very similar to the CaneBrake rifle in weight, overall length, and modularity. The MCX Virtus SB boasts the highest range of aftermarket products, with over 500 combinations of customization. I’m not a huge fan of the 31" overall length, but they specifically made the Virtus SBR with the inert training device that allows for quick, easy, and seamless suppressor attachment. 

The reason I’d choose this gun over the Rattler SBR is it offers more range with the longer barrel and overall length. The Matchlite Duo trigger is lighter than the 2-stage trigger and offers a clear advantage in accuracy with how crisp it feels and how fast it resets. 

Why Should I Choose the Sig MC Spear?

The MCX Spear is one of the most revolutionary guns that I’ve seen in years! Mainly because it’s chambered in the new and versatile .277 FURY (6.8x51mm) that can be easily converted to a 7.62x51mm NATO (M80) or the 6.5 Creedmoor. As a hunter, this rifle gives me the capability to use a semi-auto rifle with the capability to bring down any game animal we have in North America and Europe. I love the ability to handload my ammo because of the ballistic benefits associated with the reloading. 

As a soldier, the MCX Spear is a versatile rifle with a short barrel that offers the capability of a CQB and intermediate-range rifle. As many of our fellow combat vets know, the M855 sucks and doesn’t offer the stopping power needed when we’re in CQB environments. I know many soldiers who’d gladly give up a couple of pounds in weight for more stopping power and versatility. 

Why Should I Choose the Sig MCX PCB?

The MCX PCB is the most compact rifle-caliber gun Sig has produced to date, with an overall length of 23" and a barrel of only 5.5" long. The PCB Rattler is by far the easiest MCX platform to conceal in a backpack for hiking, hunting, or in your home with discretion. A 30-round capacity for the standard Magpul magazines is more than enough to establish fire superiority versus larger full-size AR-15s. The PCB Rattler is also the most affordable MCX on the list with an average price of only $2,300 right now. 

The folding minimalist stock and Sig enhanced trigger are the only things I’d change about this gun. Adding a PDW brace to the PCB would completely change the capability of the gun with the ability to fire this MCX with one hand. If you’re thinking that, you’d never want to fire a 5.56 NATO gun with one hand, the stabilizing brace provides more stability than the standard folding stock. The PCB Rattler is the perfect choice for SWAT Teams and soldiers that need to move fast in tight places, but don’t want to sacrifice the stopping power that comes with a rifle. 

Why Should I Choose the Sig MCX Virtus Pistol?

The Sig MCX Virtus Pistol is incredibly unique and versatile with 2 chamber options and hundreds of configurations to choose from. The MCX Virtus pistol in the .300 Blackout features a 9" barrel versus the 11.5" barrel for the 5.56 NATO chamber. The Virtus Pistol is a great alternative to the shorter barrel of the PCB or for those looking for more distance and recoil control. Attaching the Maxim PDW Brace will also significantly improve the capability and comfort of the pistol to allow for one-handed shooting. The Matchlite Duo trigger is incredibly light with almost no creep and an almost instantaneous trigger reset. 

Maxim Defense PDW Brace

Now that we understand what each Sig MCX is, let’s discuss how we can optimize a few MCX platforms with an aftermarket stock like the PDW Brace from Maxim Defense. The Sig MCX PCB, The CaneBrake Rattler SBR, The Sig MCX Rattler SBR, and the Sig MCX Virtus Pistol are guns to start with. A PDW brace differs from the CQB series braces by eliminating the dual QD cups and replacing them with one ambidextrous QD plate. The CQB series is also lighter and doesn’t extend out as far as the PDW brace by 0.75". 

This isn’t the time for SBR laws and regulations, but if you’re looking to get up to date on the most recent ATF SBR laws, read AR Pistol Laws and the ATF | Are They Making Pistol Braces Illegal?

Which MCX Would I Install the PDW Brace?

The Sig MCX PCB is an incredible opportunity to own a rifle-caliber gun that’s built with the best materials and advanced manufacturing equipment and processes. My biggest complaint with the PCB is the stock isn’t as sturdy as I’d like in a rifle-caliber gun. The PDW Brace features thick stainless steel guide rods to stabilize the polymer stock for better and more comfort while shooting a few boxes at the range. 

Why Do I Use The PDW Brace on a Sig MCX?

The 7075 aluminum housing is much better than the 6061 aluminum, which is most common in other companies. Maxim Defense went with the more rigid, harder aluminum housing to ensure the brace could hold up to the recoil of a 5.56 NATO bullet. The extended cheek weld is common in all Maxim Defense stocks and braces, but the SB3 Tactical forearm strap really sets the Maxim Defense PDW Brace apart from its competition.

The PDW Brace not only is compatible with all other Maxim Defense CQB series buffers, but it’s also compatible with the Standard, H1, H2, H3, and pistol buffer & springs. Perhaps, the most underrated feature of the PDW Brace is the seamless installation of the brace, because it comes with the buffer tube and spring, so there is no need to worry about whether the tube and spring can safely work with your Sig MCX.