Buy Winchester 5.56x45mm M855 Green-Tip Full Metal Jacket 62 gr. Rifle Ammunition USA855K – 20 Round Box at Gateway Armory. Take your range training and shooting competitions to the next level with this Winchester 5.56x45mm M855 Green Tip Full Metal Jacket 62 gr. Rifle Ammunition. This 5.56x45mm NATO Ammo developed by Winchester are made with high-quality brass cartridge cases and are guaranteed to provide consistent precision with every shot. Winchester 5.56 Full Metal Jacket 62 gr. Centerfire Rifle Ammo delivers a muzzle velocity of 3,060 ft/s, and we have bulk ammo options available for high-volume shooters. Stay on target and dominate the competition while using Winchester 5.56x45mm NATO FMJ 62 gr. Rifle Ammunition.M855 is often called “green tip” ammo. The tip of the projectile is marked green to denote a steel “penetrator” in the lead core.