Remington. In September 1963, the .223 Remington cartridge was officially accepted and named "Cartridge, 5.56mm ball, M193". The specification includes a Remington-designed bullet and the use of IMR4475 powder which resulted in a muzzle velocity of and a chamber pressure of 52,000 psi. In 1970, NATO members signed an agreement to select a second, smaller caliber cartridge to replace the 7.62×51mm NATO cartridge. Of the cartridges tendered, the .223 Remington (M193) was the basis for a new design created by FN Herstal. The FN-created cartridge was named "5.56×45mm NATO" with a military designation of SS109 in NATO and M855 in the U.S. These new SS109 ball cartridges required a 228 mm (1-in-9 inch) twist rate while adequately stabilizing the longer L110 tracer projectile required an even faster, 178 mm (1-in-7 inch), twist rate. The Belgian 62 gr SS109 round was chosen for standardization as the second NATO standard rifle cartridge which led to the October 1980 STANAG 4172. The SS109 used a 62 gr full metal jacket bullet with a seven grain mild steel tip to move the center of gravity rearward, increasing flight stability and thereby the chances of striking the target tip-first at longer ranges, in part to meet a requirement that the bullet be able to penetrate through one side of a WWII U.S. M1 helmet at 800 meters (which was also the requirement for the 7.62×51mm NATO). An actual helmet was not used for developmental testing, but an SAE 1010 or SAE 1020 mild steel plate, positioned to be struck at exactly 90 degrees. It had a slightly lower muzzle velocity but better long-range performance due to higher sectional density and a superior drag coefficient. This requirement made the SS109 (M855) round less capable of fragmentation than the M193. The .223 Remington cartridge inspired an international tendency toward relatively small-sized, lightweight, high-velocity military service cartridges that allow a soldier to carry more ammunition for the same weight compared to their larger and heavier predecessor cartridges, have favourable maximum point-blank range or "battle zero" characteristics, and produce relatively low bolt thrust and free recoil impulse, favouring lightweight arms design and automatic fire accuracy. Similar intermediate cartridges were developed and adopted by the Soviet Union in 1974 (5.45×39mm) and by the People's Republic of China in 1987 (5.8×42mm). Cartridge dimensions The 5.56×45mm NATO has 1.85 ml (28.5 grains H2O) cartridge case capacity. 5.56×45mm NATO maximum NATO cartridge dimensions.