SIG-550

The SIG Sauer SIG516 is a sporting rifle chambered in 5.56×45mm NATO, influenced by the Heckler & Koch HK416. Its development was led by principal engineers Robert Hirt and Chris Sirois. Their design aimed to improve upon the HK416 by using standard M4 carbine mil-spec components, addressing issues like high cyclic rate, gas vent visibility in low light, and the need for a firing pin safety. Hirt and Sirois later contributed to the SIG716, SIG MCX/MPX, and the CAR 816 series.

Based on the AR-15 platform, the SIG516 uses a short-stroke gas piston operating system, unlike the AR-15's gas impingement system. It features a four-position gas regulator, a proprietary bolt carrier, chrome-lined barrels, and a rubber wedge to minimize movement between the receivers. The safety lever is located on the left side, and the gas block is railed for front sight attachment. SIG516 models feature 16-inch barrels with a free-floating M1913 Picatinny rail and flip-up iron sights, and are equipped with an M16A2 style bird-cage flash hider. Chambered in 5.56×45mm NATO, it accepts STANAG box magazines. The SIG516 Russian, chambered in 7.62×39mm, uses magazines designed for that caliber in an AR-15 style format. The rifle is hammer-fired and is designed to meet the NATO “Over the Beach” protocol.

Variants include:

• SIG516 Precision Marksman: Features an 18-inch barrel and an adjustable stock.

• SIG716: A battle rifle variant chambered for 7.62x51mm NATO and accepting SR-25 pattern magazines.

• SIG716 G2: Utilizes a short-stroke pushrod gas system; the G2 Patrol model is chambered in 7.62×51mm NATO, while the G2 DMR model is chambered in 6.5mm Creedmoor.

• SIG 716i: Uses a gas-operated, rotating bolt (internal piston) system, chambered in 7.62×51mm NATO.

The SIG Sauer SIG516 and SIG716 are used by military and law enforcement organizations in Argentina, Canada, Egypt, Georgia, Hong Kong, India, Indonesia, Mexico, Peru, Serbia, Switzerland, Trinidad and Tobago, Turkey, Ukraine, the United Kingdom, and the United States.