The legendary performance and accuracy of the Swiss-built SG 550 tactical rifle is found in every SIG556 Classic. The Classic SWAT is a semiautomatic rifle with the silhouette that harkens back to the original military-only 550 model. Featuring a full-length gas piston operating system with a 2-position gas valve, the rifle will keep operating even when the environmental conditions deteriorate. Chambered for 5.56 NATO, the Classic SWAT features a Swiss-type folding stock, as well as a aluminum quadrail forend that is ideally suited for mounting accessories. The Classic SWAT's sleek profile and compact length is enhanced by a 16" button-rifled barrel. Sig Sauer shaved a pound off the Classic model by incorporating a redesigned alloy trigger housing, AR-style magazine, and flash suppressor. Obtaining a sight picture with the SIG556 SWAT model now takes place using a new rear rotary diopter sight, utilizing aperture calibrations from close quarter ranges out to 100m, 200m, and 300m.