Ackley Improved version of the .308 Winchester; widely discussed in precision shooting communities for its improved case capacity and reduced body taper.
Type: Rifle
Introduced: 1952, United States
Parent case: .308 Winchester
Standardization: Proprietary
Bullet diameter: 0.308" (7.82 mm)
Rim type: Rimless
Primer: Boxer Large Rifle
Production status: Active
Also known as: .308 AI · .308 Winchester AI
History: The .308 AI is one of the more commonly discussed Ackley Improved cartridges due to the .308's dominant position in precision rifle shooting. In practice the gains are modest — 50–80 fps — because the .308 already has a reasonably efficient case design. It requires custom chambering and is not in common factory production.