Definitions for ".220 Swift"
The .220 Swift was developed by Winchester and introduced in 1935. It was the first factory loaded rifle cartridge with a muzzle velocity (MV) of over 4000 ft/s (1200 m/s) and is still the fastest and most accurate factory loaded small arms cartridge, though the .218 Bee and .204 Ruger comes quite close with .20 caliber bullets of lighter weight. The .220 Swift uses .224 in diameter bullets, as do most .22 caliber centerfire cartridges.