SIG SAUER 551-A1 SBR 5.56mm

For greater versatility, the SIG551-A1’s safety selector is ambidextrous and…

For greater versatility, the SIG551-A1’s safety selector is ambidextrous and the sling attachment point above the stock is reversible.

Sig Sauer, having begun 150 years ago as a Swiss wagon manufacturer that started out in the gun business by making muskets for their nation’s military, is today manufacturing some of the best semi-automatic rifles available in the U.S. While Sig remains primarily known as a pistol manufacturer to many American shooters, especially popular among federal law enforcement, its military rifle tradition is a storied one.

“Swiss made” has long been synonymous with high quality, and when it comes to their national defense, this commitment to reliability, effectiveness and attention to detail is carried to the Nth degree. In the 1970s, Sig teamed up with German firearms firm Sauer & Sohn to manufacture pistols and import firearms to the U.S., but they never stopped working with the Swiss military—including producing the current-issue SG550.

The Swiss-style folding stock on the SIG551-A1 easily folds out of the way and brings the
SBR down to a usable 19.7-inch length.

This rifle’s reputation drove demand in the U.S. but it had been largely unavailable thanks to restrictive import laws until the company began building rifles at their Exeter, New Hampshire, facility a few years ago. In addition to a full line of AR-style and Swiss-inspired tactical rifles and pistols, they are now increasing their production line and aggressively marketing complete short-barreled rifles, or SBRs. In addition to being available to the law enforcement market, they are also offered for sale on the civilian market where legal.

The SIG551-A1 is based upon the original military Swiss SG550 series, minus the full-auto capability. It is available in two styles—one with a standard handguard, and one known as the “SWAT” model because of its quad-rail forend for adding accessories. I was given the latter for this review. This semi-automatic rifle, chambered in 5.56x45mm NATO, uses a long-stroke gas piston method of operation where the bolt and piston rod all move as one big unit, similar to that found on the AK series of rifles. This mass moving back and forth provides very reliable operation.

The piston-driven system also keeps the carbon fouling at the front of the gas system and mostly out of the receiver. This helps to reduce operating temperatures inside the receiver, and the gun requires less lubrication. It also makes cleaning a less stressful affair. At the front of the gas system, the SIG551-A1 features an adjustable valve that can be rotated to increase the gas pressure to keep the rifle running even in the case of extreme fouling, which could otherwise affect functioning. Many of the components of the gas system are also made from stainless steel to provide an added margin of corrosion resistance.

The SIG551-A1 SBR is a powerful entry weapon based on the original Swiss military SG550. Shown with Sig’s Mini Red Dot and foregrip, and a Laser Devices DBAL-I2 mounted on the optional quad-rail.

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