17 WSM Winchester Varmint | 17 Winchester Super Magnum | 17 WSM in stock 2025

17 Winchester Super Magnum is a rimfire rifle cartridge developed by the ammunition company Winchester in 2012. It descended from a .27 caliber nail-gun blank cartridge by necking down the blank case to take a .17 caliber (4.5 mm) bullet. Initial loadings were with a 20-grain (1.3 g) bullet, delivering muzzle velocities around 3,000 feet per second.