A .22 LR case necked to .17 caliber. Delivers .17 HMR-style flat shooting in a smaller, quieter package.
Type: Rimfire
Introduced: 2004, United States
Parent case: .22 Long Rifle
Standardization: SAAMI
Bullet diameter: 0.172" (4.37 mm)
Case length: 0.713" (18.11 mm)
Overall length: 1" (25.4 mm)
Max pressure: 24,000 PSI
Rim type: Rimfire
Primer: Rimfire
Typical twist rate: 1:9
Muzzle velocity: 2050–2100 fps
Muzzle energy: 159–166 ft-lbs
Effective range: 100 yd
Common bullet weights: 17 gr
Primary use: Small Game, Pest Control, Plinking
Production status: Active
Also known as: .17 Hornady Mach 2 · .17 HMR2
History: Introduced by Hornady and Eley in 2004. Built on the .22 LR case necked to .17 caliber. Designed to provide flat-shooting .17 caliber performance from rifles chambered for the more common .22 LR action.
Notable firearms: Various bolt actions
Similar cartridges: .17 HMR, .22 LR