Ball, Enhanced 5.56 mm Carbine, MK318 MOD 0: 5.56×45mm 62-grain Open-Tipped Match Boat-Tail cartridge. Optimized for use with 14-inch barreled weapons like the M4A1 Carbine and MK16 SCAR and designed to penetrate light barriers like windshields or car doors with no loss of accuracy or damage. Now designated as Caliber 5.56 mm Ball, Carbine, Barrier. SS109/M855 In 1970, NATO decided to standardize a second rifle caliber. Tests were conducted from 1977 to 1980 using U.S. XM777 5.56 mm, Belgian SS109 5.56 mm, British 4.85×49mm, and German 4.7×33mm caseless. No weapon could be agreed upon, as many were prototypes, but the SS109 was found to be the best round and standardized on 28 October 1980. The SS109 was developed in the 1970s for the FN FNC rifle and the FN Minimi machine gun. To increase the range of the Minimi, the round was created to penetrate 3.5 mm of steel at 600 meters. The SS109 had a steel tip and lead rear and was not required to penetrate body armor. Barrels required at least a 1:9 in rifle twist, but needed a 1:7 in rifle twist to fire tracer ammunition. The U.S. designated the SS109 cartridge the M855 and first used it in the M16A2 rifle. The 62-grain round was heavier than the previous 55-grain M193. While the M855 had better armor penetrating ability, it is less likely to fragment after hitting a soft target. This lessens kinetic energy transfer to the target and reduces wounding capability. The M855 is yaw dependent, meaning it depends on the angle upon which it hits the target. If at a good angle, the round turns as it enters soft tissue, breaking apart and transferring its energy to what it hits. If impacting at a bad angle, it could pass through and fail to transfer its full energy. The SS109 was made to pierce steel helmets at long range from the Minimi, not improve terminal performance on soft tissue from rifles or carbines. In Iraq, troops that engaged insurgents at less than 150 yards found that M855 rounds did not provide enough stopping power. In addition to not causing lethal effects with two or more rounds, they did not effectively penetrate vehicle windshields, even with many rounds fired at extremely close range. In Afghanistan, troops found that M855 rounds also suffered at long ranges. Although 5.56 mm rifles have an effective range of 450–600 meters,