What Makes The Sig MCX Rattler Such An Exceptional PDW?

The MCX Rattler, Sig Sauer’s flagship firearm, came into existence as a response to a need by the US Special Operations Command for a new personal defense weapon (PDW) that was lightweight, compact and powerful. Apparently, the MP-5, the hitherto PDW of choice for the elite members of the US Special Operations, has been coming short during combat. The Rattler, a short barrel rifle with distinguished with an operating system that uses a short-stroke recoil gas piston, won the approval not only of the military personnel, but just about every firearm enthusiast and professional user looking for a compact rifle that is convenient, powerful, and easy to handle.

The Evolution of the PDW

Personal-defense weapons have been around since the early special operations unit was formed and sent into combat. But the early PDWs were heavy, unwieldy and not really that effective. Case in point the 9mm submachine gun, a cumbersome piece of weaponry that was almost as weighty as a rifle but lacking the firepower and accuracy of one. So in the late eighties, the military requested a new personal weapon for the troops. This gave rise to various new designs that aimed to upgrade the 9mm with better cartridges such as the famous 5.7x28mm FN P90.

Of course, that didn’t solve the problem of weight and power. And it took almost twenty years for two major firearms manufacturers, namely Remington and Advanced Armament Corporation to work together to come up with a round as lethal as the AK 47’s 7.62x39mm but still fit in AR files and their ilk. Thus the SAAMI-standardized 300 Blackout was born. With a barrel change, any AR-style rifle could use the new designs. A later improvement brought us the subsonic and supersonic 300 Blackout loads. Those two allowed for better suppressor optimizations which suited covert-operations and hostage-rescue units much better. The 300 Blackout loads opened the door for various designs that answered every need in the market. And when Sig Sauer introduced its own 300 Blackout PDW in the form of the SIG MCX Rattler, the Special Ops finally found their coveted weapon.

The Rattler Begins

The MCX Rattler evolved from the MPX, a pistol-caliber platform that is distinguished for its operating controls and ergonomics and for years has been one of Sig’s most successful products. Before the Sig Sauer MCX, the MPX had relied on a self-regulating short-stroke gas piston mechanism that eliminated the need for a buffer system. The MCX took the best features of the MPX, added rifle-caliber power and precision to them as well as a folded stock to produce the Rattle rifles. As a modular weapon, replacing parts and upgrading its features is a simple and straightforward process. You can switch between 300 Blackout and 5.56mm easily. Moreover, installing new stocks, barrels and handguards ensure your weapon will always look and feel brand new.

As a compact firearm, the Rattler is almost unparalleled in the market. It stands at a mere 16” when folded. Extending it will give you 7” more in length. In addition, you can access all controls of the weapon even when it’s folded. This includes the ability to fire as well. Talk about convenience. In fact, one of the major goals while designing this nifty and powerful rifle was to use a specialized upper receiver to make it as compact and limited in size as possible. And Sig Sauer did manage to give us a sub-gun as small as the MP-5 without diminishing its firepower or reducing its effectiveness during a fight. To purchase a Sig Sauer MCX Rattler for sale, click here.


The Sig MCX Rattler SBR (SBR stands for short-barreled rifle) boasts of a 5.5” barrel that is the shortest in the MCX series. This exceptionally short barrel also has a slight twist rate that accommodates for heavy bullets.

It is available in both 300 Blackout and 5.56mm. The difference between those two systems makes them appeal to two different types of customers. The 300 Blackout allows for an adjustable gas block which gives you the option to use either suppressed or unsuppressed fire. The 5.56mm, on the other hand, has a gas block that will not let you fire it suppressed. That’s because the gas block uses a plug system, unlike the more flexible 300 Blackout.

But no Sig Sauer MCX Rattler review, or a review of MCX Rattler 300 BLK for that matter, will be complete without talking about its compatibility with other similar weapons. On top of the list is the short barrel of the SBR. It’s not cross-compatible with other rifles in the MCX or Vitrus series. However, any Rattle barrel can be swapped with other Rattlers. Meanwhile, Rattler uppers will work nicely on any MCX lower and Rattler lowers will fit well on M4 uppers once you’ve installed the buffer tube. This explains why these sub-guns are so popular among sports shooters and professional users alike. Omaha Outdoors has SIG MCX Rattler SBR and pistol versions.

Sig MCX Rattler PSB

Since this is a SIG MCX Rattler review, then talking about the Sig MCX Rattler PSB wouldn’t be out of place. In fact, the PSB, short for the pistol-stabilizing brace, already has its grown circle of hardcore fans who wouldn’t consider using a different firearm. So much so that Tim at Military Arms Channel on Youtube created some interesting videos about that specific firearm and others in the Rattler platform. This is not surprising considering the many features the MCX Rattler PSB has. One of which is the adjustable brace which in the absence of buffer tubes makes for a discreet and compact firearm with rifle-like powerful capabilities. Compared to other NFA SBR-classified weapons, this brace-stabilized pistol offers people a lot of advantages even those who have no legal access to NFA Class 3 weapons. This is the kind of firearm that triumphs over any handgun when a threatening situation arises away from home.

As far as personal-defense weapons go, the Sig MCX Rattler redefines the whole genre. We can talk about its compact size and rifle-caliber firepower till the cows come home and we still haven’t given it its full right. Being armed with a Rattler simply gives you the kind of confidence you don’t get from any other weapon of its caliber or size.

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