Pioneering semi-automatic pistol magnum cartridge, formed from cut-down .308 Winchester brass. The first successful semi-automatic pistol to deliver revolver-magnum performance. Achieved cult status through the Auto Mag pistol's use in films.
Type: Pistol
Introduced: 1971, United States
Parent case: .308 Winchester (cut down)
Standardization: None
Bullet diameter: 0.357" (9.07 mm)
Case length: 1.298" (32.97 mm)
Overall length: 1.6" (40.64 mm)
Max pressure: 45,000 PSI
Rim type: Rimless
Primer: Small Pistol Magnum
Typical twist rate: 1:18.75
Muzzle velocity: 1500–1610 fps
Muzzle energy: 624–810 ft-lbs
Effective range: 100 yd
Common bullet weights: 125, 140 gr
Primary use: Hunting, Target
Production status: Discontinued
Also known as: .357 AMP · .357 Auto Mag
History: Developed in 1971 by Harry Sanford for the Auto Mag pistol — a gas-operated stainless steel semi-automatic using rifle-derived brass. The Auto Mag was designed to be the most powerful semi-automatic pistol available. The Auto Mag Corporation went bankrupt several times; the pistols were manufactured inconsistently and quality varied dramatically. Lee Jurras at Super Vel loaded the factory…
Notable firearms: Auto Mag Pistol (AMT)
Similar cartridges: .44 AMP, .357 Magnum, 9mm Winchester Magnum