What is psa 5.7 rock?

PSA 5.7 Rock is a variant of the AR-15 rifle produced by Palmetto State Armory (PSA). It features a 16-inch barrel and a free-floating M-LOK handguard for improved accuracy and modularity. The upper and lower receivers are made of aircraft-grade aluminum and feature a Mil-Spec anodized finish. The rifle is chambered in 5.56 NATO and uses PMAG magazines. The PSA 5.7 Rock also includes a single-stage trigger, a billet trigger guard, and a 6-position telescoping stock. It is named after the 5.7x28mm cartridge used in the FN Five-seveN pistol and P90 submachine gun, although the PSA 5.7 Rock does not use that cartridge.