tested as a group. The test series most often includes , , , and mass RCC FSP testing. The 2-4-16-64 series is based on the measured fragment size distributions. The second part of "Casualty Reduction" strategy is a study of velocity distributions of fragments from munitions. Warhead explosives have blast speeds of to . As a result, they are capable of ejecting fragments at speeds of over , implying very high energy (where the energy of a fragment is mass × velocity2, neglecting rotational energy). The military engineering data showed that, like the fragment size, the fragment velocities had characteristic distributions. It is possible to segment the fragment output from a warhead into velocity groups. For example, 95% of all fragments from a bomb blast under have a velocity of or less. This established a set of goals for military ballistic vest design. The random nature of fragmentation required the military vest specification to trade off mass vs. ballistic-benefit. Hard vehicle armor is capable of stopping all fragments, but military personnel can only carry a limited amount of gear and equipment, so the weight of the vest is a limiting factor in vest fragment protection. The 2-4-16-64 grain series at limited velocity can be stopped by an all-textile vest of approximately 5.4 kg/m2 (1.1 lb/ft2). In contrast to deformable lead bullets, fragments do not change shape; they are steel and can not be deformed by textile materials. The FSP (the smallest fragment projectile commonly used in testing) is about the size of a grain of rice; such small, fast-moving fragments can potentially slip through the vest, moving between yarns. As a result, fabrics optimized for fragment protection are tightly woven, although these fabrics are not as effective at stopping lead bullets. By the 2010s, the development of body armor had been stymied in regards to weight, in that designers had trouble increasing the protective capability of body armor while still maintaining or decreasing its weight. See also International Medieval Combat Federation Liquid Armor Osprey body armor Notes References External links Museum Syndicate: Armor