Hornady has expanded the ranks of rimfires once again with the introduction of yet another .17 cartridge, the .17 Mach 2. Following up on its phenomenally successful .17 Hornady Magnum Rimfire (HMR), which the company unveiled in 2002, Hornady has brought to market a rimfire concept that has been experimented with for years, the .22 Long Rifle necked down to .17. More specifically, the Mach 2 is based on the LR Stinger case, which is slightly longer than the standard .22 LR. It is loaded with the same bullet as the .17 HMR, a 17-grain, polymer-tipped V-Max. Muzzle velocity is around 2,100 fps, which, as the name implies, is approximately twice the speed of sound and about 400 fps less than the HMR. Several manufacturers are already making rifles, and others are getting in line. Among the first to announce models for the Mach 2 are Marlin and Anschutz. No doubt many custom gunsmiths are already at work rebarreling existing rifles for the new cartridge. It's a no-brainer for the 10/22, one of the most popular rimfires for customizing. Look for handguns, too, especially revolvers with interchangeable cylinders for the HMR and the Mach 2. What's it for? It's powerful enough for small game and varmints at reasonable ranges, and based on early reports this newest little .17 is exceptionally accurate. That is enough for some. Accurate guns are fun to shoot, no matter what the target.