Suppressing the SIG Sauer MCX Rattler
SIG Sauer is a firearms juggernaut in a never-ending loop of research and development. New products are frequently on their launch pad. The company’s healthy suppressor division cranks out serious, hard-use products.
To understand more about SIG Sauer’s approach to research and development, you need to understand that the company has morphed into a complete systems provider. They have a serious focus on providing end users who work in harsh and dangerous environments across the globe with firearms, gear and ammunition in a comprehensive package. These developmental efforts end up benefiting all shooters.
The SIG Sauer Rattler is a prime example. The Rattler isn’t just a short-barreled rifle (SBR) with a suppressor attached, it is a suppressed system that had suppression as the primary objective from the outset. When you develop the firearm and suppressor side by side, you get a better outcome. This is the case with the Rattler and SIG Sauer’s SRD762 line of suppressors.
Suppressors in the SRD762 line are tough — their construction guarantees it. Void of an outer tube, the SRD762, SRD762-QD, SRD762Ti and SRD762Ti-QD share the same build properties, differing only in the materials used. Integrated spacers and baffles are welded together through a special process and give the suppressors incredible strength. SIG Sauer claims that this construction increases strength five-fold over other conventional tube designs.
Losing the outer tube also increases suppressor volume. There is simply more space inside for the gas to expand and cool. The SRD762 suppressors have a healthy 1¾-inch diameter, which improves noise reduction. Typically, 7.62 suppressors have a diameter of 1½ inches. A quarter-inch doesn’t seem like much, but it increases internal volume exponentially. SIG Sauer claims 50 percent more internal volume as compared to other suppressor brands.
The SRD762 and SRD762-QD are made of Inconel 718 and stainless steel. Grade 5 titanium is reserved for the SRDs with the “Ti” moniker. The differences don’t stop there.
All SRD762 variants feature wrench flats in various locations to ease the removal of a stuck suppressor. SIG Sauer intended for these suppressors to see a lot of use, and that can lead to carbon buildup without proper maintenance.
Flats on the non-QD version are located at the rear of the suppressor near the thread interface, as well as at the front of the suppressor. The flats on the QD versions are located at the rear and allow you to get a wrench over the flats and the locking tab that must be depressed to remove the suppressor.
The attachment type will be determined by how the end user plans to use the suppressor and host firearm. Hunters often have a specific rifle in mind for suppressed use, so a direct-thread option is optimal because it can be affixed and left in place. If there are multiple guns that you’d like to suppress but can’t outfit each one, then a QD or fast-attach version might be preferable.
SIG Sauer was one of the first firearms manufacturers to produce suppressors, and suppressors are part of entire systems that they offer across several platforms. The most well-known system they offer is the MCX, which was introduced at the same time as their suppressor line in 2014.
The MCX was one of the few firearms at the time to be designed with suppressed operation as a cornerstone of its functionality. The MCX has improved and evolved into their latest iteration — the Rattler.
The Rattler is revolutionary in many ways. For years, manufacturers have tried to compress the AR-15 platform into something resembling the MP5 — small, maneuverable, reliable. The MP5’s only shortcoming is the 9mm chambering. Now we have the .300 Blackout cartridge, which has boosted SBR performance by bringing a hard-hitting, .30-caliber projectile powered by pistol powder.
Even with the .300 Blackout, there still remained the challenge of making the AR platform’s gas system reliable in ever-shrinking packages. SIG Sauer’s Rattler has overcome this challenge.
The Rattler utilizes a short-stroke piston system along with dual recoil springs. The Rattler is not an AR platform, so there is no buffer tube/spring at the rear. Its operation takes place entirely within the upper receiver, allowing it to function with a folding or retractable stock. The original version of the MCX was a positive move away from the AR platform, and the Rattler is a culmination of feedback from working professionals on how to optimize the MCX for their needs.
“Anything we do with .300 Blackout has a focus on suppression,” said Patrick Hanley, SIG Sauer’s rifle product manager.
Our test version was a select-fire SBR, but the Rattler is also available as a pistol and comes with a three-position retractable pistol stabilizing brace (PSB). The Rattler has an adjustable gas block that optimizes function between subsonic and supersonic ammunition, and any of SIG Sauer’s SRD762 suppressors will fit the gun.
When asked if the Rattler was optimized for any particular suppressor model, Hanley said that the standard SRD762 was most considered during the Rattler’s development. The muzzle end of the Rattler’s barrel is tapered to mate perfectly with the Taper-Lok feature of SIG Sauer’s suppressors as well.
Shaking Out the Rattler
Suppressor spent a day with the Rattler and the direct-thread SRD762 at the SIG Sauer Academy in Epping, New Hampshire. With a 5½-inch barrel, it’s hard to comprehend just how small the Rattler is until you get your hands on it. I didn’t have high expectations for the gun, but when I pressed out the first round, I was welcomed by an extremely smooth recoil impulse. The Rattler churned away on all ammo, sub- and supersonic.
While conducting evaluations at SIG Sauer’s facility, I was offered the opportunity to use the automatic feature of the MCX — and it was my professional duty to see how it functioned. The experience was more fun and less cumbersome than I expected. Of course, there were no malfunctions.
I asked to have the Rattler outfitted with a magnified optic, and they obliged with a SIG Sauer Tango6 3-18X.
The Tango6 is longer than the entire Rattler without the suppressor and with the stock folded. This odd-looking setup let us see how well the Rattler/SRD762 combo would group. It’s a surprisingly handy little sniping package.
All groups were shot suppressed, and both subsonic and supersonic loads were tested. This combo produced a best group of 1.12 inches with the 125-grain SIG Sauer ammunition and 1.15 inches with SIG Sauer 220-grain subsonic ammo. This is better accuracy than expected from a 5½-inch barrel at 100 yards. Four of the rounds measured .87 inch. Yes, the Rattler can shoot.
Although uncomfortable to shoot prone with the metal stock, compact dimensions and lack of a bipod, the functionality of the suppressed Rattler was good. As a lefty, I didn’t notice any excessive gas blowback when firing at a slow pace. I wasn’t bothered by gas when shooting automatic, but that was a right-handed exercise.
There was a time when I believed that with such an extensive breadth of products, perhaps SIG Sauer was stretched too thin. Their continual innovation and refinement has proved me wrong. Apparently, they can do it all and do it well.
While SIG Sauer is better known for their quality handguns and less for their suppressors, as we move closer to a simpler suppressor acquisition process, undoubtedly this will change. You don’t need to own a SIG Sauer handgun or any other product to own one of their great suppressors.
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