.17 HMR

The .17 HMR (also known as the Hornady Magnum Rimfire) is a fairly common rimfire cartridge developed by Hornady and pushed to market in 2002.

The.17 HMR was created with the goal of producing a round with an extraordinarily flat trajectory. Originally Hornady wnated to achieve   the ballistics of the now defunct 5mm Remington Rimfire Magnum, which was manufactured from 1970 to 1974 and was the fastest rimfire round ever manufactured at the time. 

Because 5 mm cartridges were practically nonexistent at the time (the centerfire.204 Ruger was the only commercially accessible 5 mm round until 2004), they began to favor the commercially available .17 caliber. The natural parent case was the.22 Winchester Magnum Rimfire, not the 5mm RMR (which has a special case head size and necessitates a slightly different bolt and magazine), because it was widely accessible and significantly larger and stronger than the next biggest case, the.22 Long Rifle.

The velocities and level trajectory of the.17 caliber wildcats were not only met but far excelled by the 5mm RMR. These cartridges have decent accuracy as well.