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The Ultimate All-Purpose Survival Gun


What are the physical attributes of the ideal survival gun? Bugging out is a dynamic event defined by mobility, uncertainty, danger and chaos. A gun to pack for such an eventuality therefore needs to be compact, light, dependable and portable. Whether the weapon is tucked in a vehicle or slung across your chest, it needs to be sufficiently tidy as to not become an encumbrance.

The SIG SAUER Rattler is the smallest production rifle-caliber pistol in the world. It is also the ideal bug-out gun.

The gun needs to be an effective social tool that can do double duty as a hunting arm. The best survival weapon is the one you never have to shoot. If life really goes sideways you want to look scarier than the next guy.

The collapsible pistol stabilizing brace on the author’s Rattler is what makes this gun so versatile.

The SIG Romeo3 electronic optic takes up very little space yet keeps the gun running fast and shooting straight.

The Rattler’s stubby forearm is amply supplied with M-LOK slots.

Whether it is dissuading feral animals or dropping the errant whitetail, a proper survival gun also needs to pack enough downrange horsepower to reliably do the deed. Ammo doesn’t need to be unduly heavy or bulky, and the gun must be dead nuts reliable. In a perfect world this optimized survival tool would also be quiet so as to preserve your capacity to communicate and not unnecessarily telegraph your position. It seems that SIG SAUER has inadvertently contrived the perfect general-purpose survival weapon. They call it the MCX Rattler.

Vital Statistics

The SIG SAUER MCX Rattler is an absolutely tiny modular AR pistol featuring a piston-driven action. The gun is chambered for .300 BLK and sports Eugene Stoner’s apparently perfect ergonomics. If you have ever run an AR, the Rattler’s manual of arms will be foundational dogma.

The SIG SRD762 suppressor is tank-tough and maintenance-free.

The Rattler’s beating heart is the extraordinary SIG MCX action. The SIG MCX Virtus is a modular Information Age rendition of the original AR-15. Sporting easily interchangeable barrels, custom controls, and more than 500 potential configurations, the MCX Virtus can be optimized to be all things for all users. In its Rattler guise this is the smallest production rifle-caliber handgun on the planet.

The Rattler’s important controls are handy from each side of the gun.

From muzzle to butt, the open-tipped flash suppressor is rugged and effective. The 5.5-inch barrel is mated to a clean piston-driven action that is easily adjustable for subsonic and supersonic loads. Adjustment requires either a cartridge or a standard set of human fingers. The squat little aluminum handguard includes plenty of M-LOK slots for accessories, while the full-length top rail has ample space for optics. The Rattler dispenses with the traditional forward assist device.

Even with the SIG SRD762 suppressor installed, the Rattler remains unnaturally short.

The SIG Rattler pistol grip is a proprietary stubby sort that is easy to grab yet unobtrusive. The charging handle is in the expected place and works equally well from either side. The magazine release is replicated on both sides of the gun, and the bolt catch has a bottom pad to make it easy to lock the bolt back for inspection or servicing. The safety is mirrored on both sides of the receiver as well.

The SIG Rattler will feed from any STANAG magazine of any accepted capacity. The magazine release is replicated on both sides of the gun.

The whole gun sprouts sling sockets most everyplace. The lower is forged and includes an integral trigger guard. The real magic, however, happens in the back.

The .300 BLK is a strange hybrid round that brings bold new capabilities to Gene Stoner’s proven AR chassis. From left to right are the 5.56x45mm, the .300 BLK, and the 9mm Parabellum.

These typical 15-meter groups fired from a simple rest demonstrate the SIG Rattler pistol is rifle-accurate.

The MCX Rattler is available in a raw pistol form without a stock, as an SBR with a side-folding buttstock requiring NFA registration, and as a handgun equipped with a PCB (pivoting contour brace). I mounted mine with a sliding pistol stabilizing brace that rides on rails not conceptually unlike the buttstock of an M-3 Grease Gun. Regardless of the configuration you choose, the Rattler remains just crazy tiny. Opt for a brace and the gun doesn’t require NFA registration.

Accessorizing

SIG SAUER calls itself the complete systems provider, and they aren’t kidding. These guys sell guns, suppressors, ammunition, optics, accessories and clothing. Bring your own food and you can thrive on nothing more than what’s in their catalog. Their line of tactical glass reflects top-flight quality at competitive prices.

The SIG Rattler once nicely accessorized is the finest bug-out gun money can buy. Compact, accurate, hard-hitting and controllable, the Rattler is one mean snake.

The SIG Romeo3 micro red dot is sufficiently small to ride atop a handgun slide. An included riser mount brings the dot up to where it should be on a full-figured AR handgun like the Rattler. The SIG Romeo3 weighs about nothing, is intuitive and easy to use even under stress, and offers a basic red dot both-eyes-open sighting solution that makes a great gun awesome.

“Wow, just wow. The SIG MCX Rattler is unnaturally accurate. SIG’s professional shooters have logged 3-inch groups at 300 meters using supersonic ammo.”

The sight has a variety of light intensities to accommodate everything from bright sunshine to al-Baghdadi’s cave. The whole mechanism is nice and rugged. The Romeo3 runs off standard CR2032 batteries available most anyplace. Waterproof, fogproof and sporting a 3MOA dot, the Romeo3 is everything you need in a basic lightweight combat optic.

The SIG Rattler is the smallest production rifle caliber pistol in the world. It is also the ideal bug-out gun.

The SIG Rattler will feed from any STANAG magazine of any accepted capacity. One of the many manifest appeals of the .300 BLK cartridge is that is runs through any standard 5.56mm M-4 feeding device. However, if you want to peg the awesometer, slap a skeletonized 50-round aluminum drum from X-Products into the well.

The X-Products 50-round drum is cut from anodized aluminum and is simple to use. Turn the big wheel in front to drop the follower and slip your rounds in one at a time. The X-Products drum is at least as easy to load as a standard P-Mag while remaining just a little bit shorter.

Sporting easily interchangeable barrels, custom controls, and more than 500 potential configurations, the MCX Virtus [action] can be optimized to be all things for all users.”

The skeletonized version looks cool and lets you keep track of ammo remaining. The solid sort is incrementally heavier but more resistant to the elements. The fastest magazine change is the one you don’t have to make. For survival applications a 50-round drum from X-Products keeps you plenty prickly no matter the circumstances.

A nicely-accessorized SIG Rattler and a decent supply of .300BLK ammo makes you immune to the coming zombie apocalypse.

The SIG Rattler sports a smaller-than-normal proprietary pistol grip that helps keep the overall chassis unusually compact.

Magpul makes the cool-guy stuff. They invented M-LOK. You can mount up a Magpul angled foregrip on a pistol, and Uncle Sam won’t care. Orient that same grip at a right angle, and it becomes a felony. I have tried to understand it, I really have, but ultimately just gave up. When was the last time anything the government did make sense?

How Does She Run?

Wow, just wow. The SIG MCX Rattler is unnaturally accurate. SIG’s professional shooters have logged 3-inch groups at 300 meters using supersonic ammo. While there is no imaginable circumstance under which one might ever take a real shot at ranges such as those it is nice to have the capability.

The .300 BLK round offers trivial recoil as well as hearing-safe acoustics in its subsonic form through a SIG suppressor. Supersonic rounds are not awful on the ears, but the gun is really in its element with the slow stuff. The Rattler slithers around corners and maneuvers within an automobile like the souped-up handgun that it is. The PSB offers a firing platform that is more stable than any conventional pistol. Thread off the can and collapse the brace, and the gun will hide in the center console of your pickup truck.

With the SIG Rattlehe lack of noise and recoil combined with Eugene Stoner’s inimitable ergonomics means that I could double-tap targets out to 50 meters without trying hard. When firing from a rest and taking my time I could produce single ragged holes all day long at 15 meters. Out to 100 meters and beyond the velocity discrepancies between supersonic and subsonic rounds do become significant. However, when I plan my ammo and sight settings for my intended application the gun shoots better than do I.

With the can in place, the gun is sufficiently front-heavy to eliminate any noteworthy recoil or muzzle climb. The suppressor also keeps your fingers healthy, vibrant and right where God put them in the first place. Without the suppressor you do need to mind your digits when moving quickly. The angled foregrip helps a lot, but this gun is tiny. It wouldn’t do to let that support hand wander.

Denouement

Truth be known, if you have to bug out in a crisis you’d likely be fine with a used $100 pawn shop Hi-Point and a couple of spare mags. Like life insurance, none of us buys guns really expecting to use them for real. However, you might be That Guy who finds his minivan surrounded by insensate Antifa protesters determined to eat his kids for dinner. In that case nothing screams, “Pick a different car, dude!” like a tricked-out SIG Rattler MCX 300B sporting a sound suppressor and a 50-round drum.

Even if you don’t have to shoot your way out of Zombieland, the SIG Rattler is more fun than a barrel of monkeys on the range. Ammo is not as common as 5.56mm, but if you can dump this kind of coin on a top-end survival gun, pony up for a thousand rounds of .300 BLK and half a dozen spare magazines and await the apocalypse secure in the knowledge that you’re the apex predator.

The .300BLK for Hunting  and Survival

For genuine survival applications you will probably never take a shot against any two-legged threat at anything more than bad breath range. Pack that heavy long-range precision rifle if you want, but if you shoot somebody a kilometer distant and civilization doesn’t actually end you’ll spend the rest of your natural days turning big rocks into little ones in the state pen. Hunting applications might reach out a bit, but the argument can be made that the perfect survival round is the .300 BLK.

“When fitted with a SIG SRD762 sound suppressor and running subsonic ammo, the Rattler is lyrically quiet. These cans are built like armored fighting vehicles yet are still not unduly heavy.”

The .300 BLK cartridge has gone from oddity to reliably mainstream in a few short years. There are even a few spooky high-end military organizations that purportedly use the round operationally. Jason Imhoff is the guy who thought up the .300 BLK in the first place, and he is SIG’s director of ammunition engineering. The true strength of the .300 BLK cartridge rests in the fact that it uses a standard 5.56mm bolt carrier group while offering both subsonic and supersonic velocities dependent upon bullet weight.

Supersonic loads are plenty spunky for hunting whitetail deer down here in the Deep South where I live. Subsonic rounds through a proper sound suppressor are just stupid quiet. The Rattler lets you pick your poison.

Keeping It Quiet

Rumor has it that the MCX Rattler was originally contrived to fill a tactical need for some of America’s most high-speed special operators. These guys needed rifle-caliber firepower that would hide unobtrusively inside a gym bag. The SIG SAUER Rattler SBR’s compact dimensions, inimitable cool factor, and .300 BLK chambering just beg for a sound suppressor.

You’ve got to be careful when running a weapon this small that you don’t allow your support hand to slip forward and inadvertently de-finger yourself. My angled foregrip from Magpul helps keep my fingers attached and in good working order. However, thread a SIG SRD762 can on the snout and that’s no longer a concern.

The SIG Rattler is both powerful and easily controllable throughout its performance envelope.

When fitted with a SIG SRD762 sound suppressor and running subsonic ammo, the Rattler is lyrically quiet. These cans are built like armored fighting vehicles yet are still not unduly heavy. SIG cans are made from Inconel 718, a nickel alloy stainless steel that is also liberally used in core components of nuclear reactors.

The SRD762 is a sealed tubeless design that is radically effective, maintenance-free and unimaginably rugged. There is even a series of spiky bits on the snout should you need to prod some recalcitrant zombie.

Mounting up the SRD762 involves removing the original flash suppressor and threading on the can. There’s nothing to take apart, and the can is rated for both short .300 BLK barrels and heavy .300 Win Mag cartridges. Anything smaller that will fit through the bore is fair game as well with an appropriate mounting solution.

SIG SAUER MCX Rattler

Specifications

  • Caliber: .300 BLK
  • Weight: 6 pounds, 1 ounce
  • Length collapsed: 19.2 inches
  • Length extended: 23.6 inches
  • Barrel length: 5.5 inches with a 1:5 twist
  • Action: Adjustable gas piston
  • Handguard: 5-inch M-LOK

MSRP: $2,719

Sig Sauer .300 Blk MCX Rattler Performance Results

 

AMMUNITION VELOCITY

(fps)

GROUP SIZE (inches)
SIG SAUER 220-gr FMJ Subsonic 890 2.0
Gorilla Ammo 125-gr MatchKing 1,776 0.8
HPR 220-gr HPBT 902 0.8
Hornady 125-gr JHP 1,719 0.6

 

Group size is best four of five shots measured center to center fired from a simple rest at 50 meters using the SIG SAUER Romeo3 red dot sight.

Velocity is the average of three shots across a Caldwell Ballistic Chronograph oriented 10 feet from the muzzle.

FMJ=Full Metal Jacket

FPS=Feet Per Second

HPBT=Hollow Point Boat Tail

JHP=Jacketed Hollow Point

 

Editor’s note: A version of this SIG Rattler review first appeared in the March, 2020 print issue of American Survival Guide.