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.[3] 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.[4]
The first major company to produce the 7mm STW was A-Square in 1994.[5] The 7mm STW graduated to commercial status when it was officially recognized by SAAMI in 1996.,[6] and the Remington Arms Company started to produce it in 1997,[7] 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.[8]