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.