[8] The rifle features a short-stroke piston mechanism as opposed to the semi-direct impingement system of the AR-15.

The bolt carrier features an integral lug in place of the AR-15's gas key.

[9] The 5.56 rifle includes a number of other manufacturer's parts such as a Troy Industries railed handguard and Samson folding iron sights, a Hogue rubberized pistol grip, and three Magpul PMAG 30-round STANAG magazines.

The SR-556SC comes with three 10-round magazines and does not have the flash hider or collapsible stock, making it compliant in several states with restrictive rifle laws.

[4] In August 2010, Ruger announced that the rifle would be offered in the 6.8mm Remington SPC cartridge.