The Sig 556 is designed to be a gas-operated piston driven rotating bolt design, and chambered in 5.56 NATO / 223 Remington, the Sig 556 rifles are not only reliable, but accurate. The Sig rifle also features ambidextrous controls, as well as ambidextrous safety. With additional features like picatinny flat top, collapsible or folding stocks, flip up sights, and adjustable gas system.
The SIG556® Classic carries a tactical heritage that has served special operations groups, law enforcement agencies, and counter terrorism units throughout the world. When assignments depend on exceptional performance and reliability, tactical operators depend on SIG SAUER® rifles. New for this year is the introduction of the SIG556 Classic model. The Classic name is based on the rifles Swiss heritage and the classic features that it draws from those world famous Swiss rifles. The adjustable stock snaps and securely locks into a folded position with a length-of-pull that can be preset by the user. The clean tapered forend styling allows for a firmer grip and better control. The redesigned trigger housing improves access to functional controls while improving the overall ergonomics of the rifle. The SIG556 operating system is topped off with a red dot sighting system that ensures quick target acquisition.
theSIG SG-552, is similar to SIG SG-551 but it has even shorter hand guard and barrel. Due to short barrel and gas piston,SG-552 has return spring relocated to the rear part of the receiver,and thus it has an altered bolt carrier and upper receiver. The gas port has gas regulator with two different open and one closed position (latter for firing rifle grenades).
The receiver of all SG-55 series guns is made from stamped steel and has two majorparts, upper and lower, which are connected by push pins. The barrel is screwed into the upper receiver. The trigger unit has a safety/fireselector switch on the left side of the receiver, with 3 settings:safe, semi-auto, full-auto. If desired, additional module could be installed in the trigger mechanism to allow 3-rounds burst mode. Rearsights are drum-type (like those found on Heckler-Koch rifles).