The most powerful rimfire cartridge available. Bridges the gap between .22 WMR and centerfire varmint rounds.
Type: Rimfire
Introduced: 2012, United States
Parent case: .27 Winchester nail gun blank
Standardization: SAAMI
Bullet diameter: 0.172" (4.37 mm)
Case length: 1.2" (30.48 mm)
Overall length: 1.35" (34.29 mm)
Max pressure: 33,000 PSI
Rim type: Rimfire
Primer: Rimfire
Typical twist rate: 1:9
Muzzle velocity: 2600–3000 fps
Muzzle energy: 300–400 ft-lbs
Effective range: 200 yd
Common bullet weights: 20, 25 gr
Primary use: Varmint, Small Game
Production status: Active
Also known as: .17 Winchester Super Magnum
History: Introduced by Winchester in 2012 based on a nail gun blank case. The highest-pressure and highest-velocity production rimfire cartridge. Positioned as the ultimate rimfire varmint cartridge.
Notable firearms: Winchester Model 1885, Savage B.Mag, Ruger American Rimfire
Similar cartridges: .17 HMR, .22 WMR