SIG Sauer’s SIG556 Classic SWAT proved to be accurate, reliable and soft shooting--if a bit on the heavy side for a 5.56x45 carbine.

The Swiss have always marched to their own drum when it comes to military rifles. From the 1880s until after World War II they issued manually operated straight-pull repeaters designed by Rudolf Schmidt.

In the 1950s, the old straight-pulls were dumped for the Buck Rogers-looking Sturmgewehr 57. Utilizing a roller-delayed blowback action, the 12.5-pound 7.5x55 Stgw. 57 was accurate and far reaching. Very different than its contemporaries, it was also extremely heavy and very expensive.

The beautifully crafted but portly Stgw. 57 was replaced by the Sturmgewehr Modell 90 in 1984. Also known as the SIG 550, the Stgw. 90 was a modern assault rifle chambered for the 5.56x45 cartridge. In place of the odd blowback action of its previous design, SIG (Schweizerische Industrie-Gesellschaft) developed a gas-operated system.

It featured a rotating bolt and carrier assembly that is little more than a knock-off of Mikhail Kalashnikov’s Avtomat. Fitted with an adjustable gas system and built on a stamped receiver, SIG’s 550 series earned a reputation for being extremely well-made, very reliable and surprisingly accurate.

Unfortunately, the semiauto-only version of the SIG 550 is uncommon in the United States. Specimens run upwards of $7,000. While few people have seen this series of rifle, let alone shot one, there was a great deal of interest in them.

SIG eventually responded with its 556 line to cater to the U.S. market, and one of its latest introductions is the 556 Classic SWAT. This model adds a railed fore-end and a collapsible/side-folding stock that’s reminiscent of the 550 series.

Like the standard 556 series, the Classic SWAT is built on a stamped steel upper receiver. Riding inside this is a Kalashnikov-type bolt and carrier. However, unlike the Kalashnikov the gas piston is a separate component retained to the bolt carrier via the charging handle. The recoil spring, which encircles the gas piston, is captive. A multi-position regulator allows the rifle to be adjusted for the conditions and ammunition.

Fitted to the front of the upper receiver is a 16-inch, military-grade, cold-hammer-forged barrel with six-groove rifling and a 1:7 twist. The barrel features standard 1/2x28 TPI threads and is fitted with an effective flash suppressor. This unit also acts as a mount for sound suppressors.

The upper receiver sports a 1913 rail for mounting optics and is fitted with a vented quad-rail fore-end.

The upper mounts to an aluminum lower via two push-pins. Unlike the original 550 series, the SIG556 feeds from standard AR-15/M16 magazines. The lower has ambidextrous safety levers, along with a push-button M16-type magazine release and bolt release.

The 556’s skeleton stock both folds and collapses. With the stock fully extended, the Classic SWAT is 37.8 inches long. This drops to 35 inches with the stock fully collapsed. Fold the stock to the side and the Classic SWAT is only 26.5 inches. It tips the scales at 8.3 pounds without mag.

The Classic SWAT feels fairly good but I think it’s front-heavy. Start adding optics and accessories, and it gets heavy fast. During testing, I noted the magazine release is a bit of a stretch compared to an AR, but mags inserted easily and ejected cleanly.