7mm Shooting Times Westerner

The 7mm Shooting Times Westerner, sometimes referred to as the 7mm STW, began as a wildcat rifle cartridge developed by Layne Simpson, Field Editor of Shooting Times, in 1979. It is an 8mm Remington Magnum case that has been "necked down" (narrowing the case opening) by 1 mm to accept 7 mm (.284 in) bullets.

Background
The first major company to produce the 7mm STW was A-Square in 1994. The 7mm STW graduated to commercial status when it was officially recognized by SAAMI in 1996., and the Remington Arms Company started to produce it in 1997, with other ammunition manufacturers following. As of 2019, Federal Premium Ammunition is the only major manufacturer to still offer it on a regular basis, but smaller manufacturers also provide loaded ammunition.