Introduced in 2014 as an entry-level AR-15 using a direct impingement action, with variants since being released such as the upgraded AR-556 MPR (multi-purpose rifle) in 2017[1] and the AR-556 pistol in 2019.

The bolt is machined from 9310 alloy steel, and the furniture included is a CAR-15 style handguard without aluminum heatshields, an M4 buttstock, and a Ruger designed pistol grip.

The gas block and sight post design is proprietary to Ruger and includes a quick detach sling swivel socket and bayonet lug.

[3] The MPR model uses a 9 in (230 mm) mid-length gas system and a radial port muzzle brake, and also includes a free-float handguard with M-LOK accessory slots and a continuous top picatinny rail, and either a Magpul or B5 Systems buttstock and pistol grip.

The Protection of Lawful Commerce in Arms Act limits the legal liability of gun manufacturers.