The .357 Auto Mag, often referred to as the .357 AMP (Auto Mag Pistol), is a powerful semi-automatic cartridge designed specifically for the Auto Mag pistol. Developed in the late 1960s by Harry Sanford, the cartridge is essentially a .44 Auto Mag case necked down to accept a .357-inch diameter bullet.
This cartridge was created to provide a high-velocity, flat-shooting round with significant stopping power suitable for hunting and silhouette shooting. The .357 AMP typically launches a 158-grain bullet at velocities exceeding 1,600 feet per second, delivering substantial energy on target.
The Auto Mag pistols chambered for the .357 AMP were notable for their robust construction and distinctive appearance, but the firearms and the cartridge never achieved widespread popularity due to production challenges and high costs.
Use cases for the .357 Auto Mag include big game hunting and target shooting, particularly in contexts where high velocity and significant impact energy are desired. However, due to its rarity and specialized nature, it is more of a collector's item today.