Winchester Varmint High Velocity ammunition was developed as a fast, extremely accurate line for varmint and predator hunters. Loaded with clean burning powder and premium, trusted bullets that deliver explosive expansion. Varmint HE ammunition delivers excellent terminal performance producing quick, humane kills. The revolutionary 17 Winchester Super Magnum is the fastest, most innovative rimfire cartridge ever developed. Based off of a 27 caliber power fastener blank, this cartridge produces centerfire velocities and energy in a more cost-efficient rimfire package.