Winchester officially announced the .17 Winchester Super Magnum cartridge today, and it does appear to be the fastest and most powerful rimfire cartridge ever. Two flavors have been announced so far; a 20-grain bullet reaching 3,000 feet per second, and a 25-grain bullet traveling at 2,600 feet per second. Muzzle energy on the 20-grain loading is rated at 400 foot pounds, with the slower 25-grain loading measuring 375 foot pounds. By comparison a standard 115 grain 9mm Luger round generates around 330 foot pounds of muzzle energy, so this sort of performance from a rimfire is a true breakthrough. Case capacity exceeds any previous rimfire caliber, and the latest generation ballistic tipped bullets will be utilized immediately in factory loadings. Suddenly, it is realistic to score a humane kill on a …