The Sig Sauer Sig 556 Classic SWAT is a semi-automatic tactical carbine chambered in 5.56 NATO. The SWAT is almost identical to the standard model, but the SWAT has a trimmed down alloy trigger housing, which Sig says weighs less, and four Picatinny rails for easy mounting of optics and accessories.
The SWAT uses a gas piston operating system, which functions by propellant gases entering a port near the muzzle, the gas enters a tube that’s directed onto a piston and the piston connects with the bolt and pushes it rearward.
Other features include a cold hammer forged barrel, so a machine carefully cut the grooves in the bore. This produced durable rifling. The stock is collapsible for storage, but also adjustable for length. It has a rotary diopter rear sight, which provides four sight stations: CQB, 100m, 200m and 300m, and is also adjustable for elevation and windage.
Sig Sauer recommends the Classic for law enforcement and responsible civilians.