5.56x45mm MK 318 Mod 0 (SOST)

A 5.56x45mm NATO MK 318 Mod 0 (SOST) cartridge with a 4 gram open-point bullet with a lead core over a copper base with a copper jacket, in a brass case. The cartridge was specially designed for the United States Marine Corps, under the name SOST (Special Operations Science and Technology) to provide penetration of objects with low structural strength and provide a considerable stopping power effect, even being able of piercing basic ballistic body protections.