The HK USC (Universal Self-loading Carbine) is a semi-automatic carbine manufactured by Heckler & Koch, chambered in .45 ACP with a 16-inch barrel. It uses a blowback-operated system and features a durable polymer frame with corrosion-resistant finish. The design is derived from the HK UMP but configured for civilian legal sale. The USC includes a Picatinny rail for optics and a thumbhole stock. Its proprietary 10-round magazine feeds reliably and meets restrictions in many jurisdictions.