.220 Swift

The prototype for the.220 Swift was developed in 1934–35 by Grosvenor Wotkyns who necked down the.250-3000 Savage as a means of achieving very high velocities. However the final commercial version developed by Winchester is based on the 6mm Lee Navy cartridge necked down, but besides inheriting headspacing on its rim from the parent, a feature already considered obsolete by the 1930s, the protruding rim which complicates loading was even made larger to fit with 12mm-wide.30-06 bolt faces. The.220 Swift was developed by Winchester and introduced in 1935 as a new caliber for their Model 54 bolt-action rifle. When the Winchester Model 70 bolt action was first issued in 1936, the.220 Swift was one of the standard calibers offered and continued to be until 1964 when it was discontinued.

The Swift has the dubious privilege of being possibly the most controversial of all the many.224" caliber cartridges, and has inspired equal heights of praise and criticism. Traditionalists have roundly condemned it as an overbore "barrel burner" which can wear out a chromoly barrel in as few as 200–300 rounds, especially if long strings of shots are fired from an increasingly hot barrel. Its supporters have maintained that the fault lies with poor-quality barrel steels and the failure of users to remove copper fouling after firing, and point to instances of rifles with fine-quality stainless steel barrels chambered for the Swift, which have maintained sub-MOA precision after well in excess of 4,000 shots. More popular, however, is the smaller and slightly lower velocity.22–250.

Due to the cartridge being over capacity for the bore diameter and the extreme velocity of the projectiles, throat erosion is a common problem. Modern metallurgy and cryogenic treatment have vastly improved barrel life with the.220 Swift and other 4,000 ft/s (1,200 m/s) cartridges, although weapons firing these cartridges still usually require rechambering or rebarreling much sooner than those firing lower-velocity cartridges such as the.222 Remington and the.223 Remington.

The Swift remains a controversial deer caliber. Its use is prohibited in some US states and much of Europe, including England, Wales and Northern Ireland for large deer such as red, sika and fallow, but two-thirds of the United States, such as Minnesota, Idaho and Montana, currently allow smaller caliber rounds like the.220 Swift to be used. It is legal for use on game in New Zealand and Australia. In the cartridge's early days in the 1930s, its killing power on large ungulates was extolled by famous Scottish hunter W. D. M. Bell for stalking red deer as well as Alaskan wildlife control officer Frank Glaser. This was attributed by gun writers to massive hydrostatic shock waves set up in the animal's body by the impact of the very high-velocity bullet. However, Bell considered the Swift to be a risky cartridge for the normal heart or lung shot, as the light high velocity bullet was liable to break apart if it hit large bones. When hunting red deer he almost exclusively shot for the neck. Critics of the Swift have maintained that the light, 50-or-55-grain (3.2 or 3.6 g), bullet leaves an inadequate margin for error in bullet placement for the average deer shooter's skills, and thus invites wounding, which would have otherwise been avoidable. There is, however, little debate about the Swift's proven effectiveness on small deer species, such as roe, provided very fast-fragmenting "varmint"-type bullets are not used. Most factory Swift rifles come with a fairly slow twist-rate such as 1–12 or 1–14 inch, designed to stabilize the lighter bullets popular in varmint hunting. Custom Swifts can have faster twist-rates such as 1–9 inch allowing them to stabilize heavy bullets, including those with a construction suitable for larger game. P. O. Ackley maintained that the.220 Swift was a fine round for medium-large game and used it extensively, for example when culling wild burros in the American West. Famous Alaskan wildlife control officer Frank Glaser also utilized the caliber extensively on all sorts of big game, including moose, caribou, Dall sheep and wolves. Glaser claimed that with lung shots the Swift would produce more instantaneous kills than any other cartridge he had ever used. He considered the light 48 grain bullet inadequate against grizzly bears though, and although he killed several with the Swift, on one occasion it took eleven shots to put down a sow that had attacked him.