.17 HMR

The .17 HMR necks the .22 Winchester Magnum Rimfire case down to hold a 4.4mm bullet, a project Hornady completed in 2002 to build the flattest-shooting, most accurate rimfire cartridge then on the market. Its very light, high-velocity bullets give it noticeably less bullet drop and wind drift than the .22 WMR it is built from, at the cost of the heavier parent cartridge’s usefulness on larger varmints, and it has become a common choice for shooters who want a rimfire able to reach out past 100 metres with a flat trajectory rather than one built primarily for close-range small game.

Being a rimfire design, it is loaded and fired exactly as its parent case is, with the priming compound distributed around the inside of a solid rim rather than struck by a separate primer — the same mechanism used by .22 Long Rifle, scaled up in pressure and case capacity. Hornady, CCI, Federal, PMC, Remington and Winchester all load it.

Every dimension in this entry comes from the C.I.P. datasheet for “17 HMR”. Both loads are Hornady’s own factory products — the 17-grain V-MAX and the heavier 20-grain XTP — with bullet mass and muzzle velocity read directly from Hornady’s own product pages, each stating a 24-inch test barrel. Neither page publishes a ballistic coefficient anywhere in its static content, despite marketing prose describing the round’s flat trajectory, so no ballistic coefficient is recorded and no trajectory beyond muzzle figures can be computed here.