Low prices on the Sig Sauer 556 Classic SWAT start at Champion Firearms- the Sig Sauer 556 Classic is the civilian version of the legendary Swiss SG550 military rifle. Like the SG550, the 556 shares the same ultra reliable gas piston system, along with a pressed steel upper receiver. Unlike the Swiss SG550, the Sig Sauer 556 has a lightweight 7075-T6 forged aluminum alloy receiver (vs pressed steel), reducing the rifle's overall weight by over a pound. To make it even more user friendly, Sig also redesigned the 556 magazine well to readily accept standard AR-15 magazines.
The SIG556 Classic has a triangular shaped synthetic stock patterned on the SG550 and is adjustable for length of pull. The synthetic, two- piece forend is also similar to the SG550, with a streamlined shape and molded ribs. Controls of the SIG556 Classic SWAT are simple and straightforward-- an ambidextrous safety is located above a ribbed synthetic pistol-grip assembly. An AR-15-style magazine-release button is located forward of the trigger guard, and a bolt-release lever is situated on the opposite side of the lower receiver. A reciprocating charging handle extends out of the bolt carrier assembly through the ejection port.
Operationally, the SIG556 is a gas-operated, rotating-bolt carbine with a two-position gas system driven by a piston. The setting of the gas system can be adjusted by twisting the gas valve located on the forward face of the front-sight base assembly. When the valve is vertical, the rifle is set on the "standard" setting; when it is rotated 45 degrees, it is on the "emergency" setting that allows more gas through.
The cold-hammer-forged, 16-inch barrel of the SIG556 ends in a birdcage-style flash hider and features a slim profile. The rifling's rate of twist is 1:7 inches, making it suitable for stabilizing a wide range of even the heaviest .223 Rem. loads. The SIG556's upper receiver has a built-in Picatinny optics rail that includes a heavy-duty steel diopter rear sight.