 Chambered in .222 Remington in early prototypes, the short barrel produced significant noise and muzzle flash.Subsequently the case was shortened to reduce powder capacity to a volume more suited to the shorter barrel of a pistol.The resulting cartridge, the .221 Fireball, produced factory loaded velocities of over 825 m/s (2,700 ft/s) from the short barrel, and accuracy rivaling the parent .222 Remington, one of the most accurate cartridges made.