Winchester's proprietary semi-rimmed rimfire cartridge developed for the Model 1903 semi-automatic rifle. Features a semi-rimmed case and greased bullet suited to the blowback action of the Model 1903.
Type: Rifle
Introduced: 1903, United States
Parent case: None
Standardization: None
Bullet diameter: 0.224" (5.69 mm)
Case length: 0.7" (17.78 mm)
Max pressure: 25,000 PSI
Rim type: Rimfire
Primer: Rimfire
Typical twist rate: 1:16
Muzzle velocity: 1000–1055 fps
Muzzle energy: 100–112 ft-lbs
Effective range: 75 yd
Common bullet weights: 45 gr
Primary use: Small Game, Target
Production status: Discontinued
Also known as: .22 Win Auto · .22 WA
History: Introduced in 1903 alongside the Winchester Model 1903, America's first semi-automatic .22 rimfire rifle. Winchester's engineers designed a unique cartridge to ensure proper feeding in the new action. Production ended mid-20th century as .22 LR dominance made proprietary cartridges uneconomical.
Notable firearms: Winchester Model 1903, Winchester Model 63
Similar cartridges: .22 Long Rifle, .22 Remington Automatic