Following the stunning success of the 17 HMR Hornady introduced the 17 Mach2 in 2004. The 17 Mach2 is based on the 22 Long Rifle case necked down to accept a 17-caliber bullet. Bullet weights are the same as for the 17 HMR, 17 or 20 grains, and while it is not as fast or as powerful as the 17 HMR it delivers amazing performance from so small a case: 17-grain bullet at 2100 feet per second; 20-grain bullet at 1800. No 22 Long Rifle load approaches it in velocity, so it is at least as effective for small game and small varmints, offering a much flatter trajectory with generally excellent accuracy. Most major firearms manufacturers offer 17 Mach2 firearms, but consistent functioning in semiautomatics has proven challenging, so it does not approach either the 22 Long Rifle or 17 HMR in overall popularity.
