The SIG Sauer 556 Classic SWAT (Special Weapons And Tactics) rifle was the gunmaker’s attempt to bring an updated version of the SIG 550 series of rifles to the North American shooting market. Although not popular, it remains a high-quality rifle with a dedicated following.

When it became available on the market, the AR-15 had long been standardized and was considerably cheaper than the SIG Sauer 556. During the whirlwind of the anti-gun movement at the time, consumers opted for familiar rifles like the AR-15 over new, unfamiliar ones like the SIG Sauer 556 Classic SWAT.

I have been intrigued by the SIG family of rifles for years. Rock-solid durability, a reputation for always going “bang” when you pull the trigger—what’s not to like? When I had the chance to acquire a SIG Sauer 556 Classic SWAT with a very low round count, I seized the opportunity.

If I had to describe the SIG 556 Classic SWAT, I would say it’s the best parts of the AR-15 combined with the AK-47, with a touch of Swiss style and quality control. The rifle uses the standard AR-15 magazine and fires the 5.56×45 cartridge but employs an adjustable AK-47 type of gas system. It’s appealing to those who own AR-15 magazines and seek something different from the standard AR-15.

For readers unfamiliar with the SIG 556 family of rifles, here’s a comparison to the AR-15:

What’s Similar to the AR-15?

  • Barrel length
  • Uses standard AR-15 magazines
  • Magazine release and location are the same as the AR-15
  • 5.56 NATO chambering
  • 1:7 twist rate

What’s Different?

  • Different trigger
  • Stamped steel vs. aluminum upper receiver
  • Different bolt
  • Different recoil system
  • Bolt release operates slightly differently

Appeal to Former Military Members

The SIG Sauer 556 Classic SWAT has several features that make it especially appealing to former military personnel. For veterans familiar with the AR-15 and AK-47 platforms, the 556 offers a blend of both, allowing for an easy transition while still providing a unique shooting experience. Its chambering in 5.56 NATO and compatibility with standard AR-15 magazines cater to those accustomed to military-issue rifles, offering familiarity in handling and logistics. Additionally, the rifle’s adjustable gas piston system is built for reliability, especially when operating in harsh conditions, something ex-military shooters often appreciate after years of handling firearms in challenging environments.

Beyond functionality, the SIG 556 Classic SWAT’s durability and precise engineering reflect the kind of rugged quality that former service members expect from their weapons. Its side-folding stock and customizable features, combined with the precision of Swiss manufacturing, give it a tactical edge that ex-military users can respect. For those who miss the dependable feel of their military-issued rifles but seek something with a bit more individuality, the SIG Sauer 556 SWAT is a practical yet sophisticated alternative that bridges the gap between military and civilian use.

SIG 556 classic rifle
(File photo)

Breakdown and Operation

Owning a SIG 556 rifle has shown me how easy it is to become familiar with it. As an AR-15 and AK-47 owner, transitioning to the 556 was natural. The receiver breaks down like an AR-15 using two push pins to separate the upper and lower halves.

However, the bolt is different. Instead of an AR-15-style charging handle, it has one on the bolt, similar to the AK-47, but it is removable to allow the bolt to slide out the rear like the AR-15. This hybrid design combines elements of both rifles.

Once the bolt is out, it resembles a modified AK-47 bolt carrier group. You can see the pronounced angled ramp on the rear of the bolt and the rotating head with locking lugs. The AK-47 pattern bolt accepts a recoil spring from the rear, while the SIG 556 bolt uses a piston system, with the recoil assembly meeting the carrier above the bolt. The lever on the SIG bolt is used to remove the charging handle.

(File photo)

Different Style of Trigger

The SIG Sauer 556 Classic SWAT trigger is unique. Unlike the traditional hinged trigger, the SIG trigger rotates back to contact a plunger assembly, releasing the hammer. Although it has a moderate amount of travel, the resistance is slight. The trigger engages the plunger smoothly, with no hard shelf to break over. It feels long, like an MP5, but better.

(File photo)

Other Features

The SIG Sauer 556 Classic SWAT includes a two-position gas piston system. According to the manual, if ejection and feeding problems occur due to heavy fouling, the gas valve can be set higher, allowing more gas into the piston assembly to prevent jams. This can help shoot lower-pressure ammo without cycling problems.

The gas system disassembles easily by pushing a detent, rotating the assembly a quarter turn, and removing it from the muzzle end. Reassembly is also straightforward, ensuring easy maintenance.

The SIG 556 Classic SWAT also has side-folding stock in a non-adjustable “Swiss Style” or a collapsible side folder similar to common AR-15 stocks. Adapters are available to install an M4 style tube and mil-spec AR-15 stock.

Author’s Image: Adjustable gas block shown in the “Dirty” position

Though the SIG Sauer 556 Classic SWAT is no longer produced, its appeal remains. It is not to be confused with the SIG Sauer 556 Xi or the SIG Sauer 550 rifle, which are separate lines. Additionally, SIG’s Piston Drive AR-15 is sometimes called the model 556, which can cause confusion. However, each model offers unique features and advantages for different preferences and needs.

My plan for this rifle is to test it with a SIG Sauer Romeo 7 or a Nikon 1x-4x BLACKFORCE 1000 scope, running at least 1,000 rounds through it. These tests will focus on durability and accuracy rather than extreme conditions.

We hope you enjoyed this look at the SIG Sauer 556 Classic SWAT. Look for the range review in the near future. Below are the rifle’s specifications from the SIG Sauer manual.

Specifications

  • Caliber: 5.56mm NATO
  • Overall Length: 37.0”
  • Length Stock Folded: 27.2”
  • Barrel Length: 16″
  • Rifling: 1 in 7″
  • Weight: 8 lbs

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