ft/s (840 m/s) 1,293 ft·lbf (1,753 J ) Test barrel length: 24 inches (61 cm) Source: Federal Cartridge [1] The .223 Remington is a sporting cartridge with almost the same external dimensions as the 5.56x45mm NATO military cartridge. It is loaded with a 0.224-inch (5.7 mm) diameter, jacketed bullet, with weights