17 HMR Ammo Development Hornady Developed the 17 HMR by taking the 22 WMR case and necking it down to accept a .172” diameter bullet. Initial factory loads from Hornady sported a 17 grain Spitzer V-MAX bullet fired at 2,650 fps. bulk 17hmr ammo The 22 Winchester Magnum Rimfire (22 https://reloadprimer.com/product/50-rounds-of-17hmr-ammo-by-winchester-20gr-jhp/