The .17 Hornady Magnum Rimfire
is the latest innovation in rimfire cartridges since Remington
created and flopped with the 5mm Remington
in 1970. The last successful
rimfire cartridge was the .22 WMR
which was invented back in 1959.
The idea was to create a 17 caliber cartridge that would outperform all of its predecessors. With the help of Ruger and Marlin, Hornady was able to make this idea into a reality.
Using a .22 WMF case necked down to accept the .172 caliber hollowpoint vmax bullet with a polymer tip, over a charge of Hodgdon Lil' Gun powder Hornady was able to create a rimfire cartridge that fired its projectile in excess of 2,500 feet per second.
This gave this varmint round a very flat trajectory and hits were possible out to 125 yards.
The .17 HMR has been accepted very well by the rimfire shooting community and rifle makers from as far as Germany have announced that they will produce rifles for this new cartridge.
The only issue for now is the price, for the cost of one box of .17 HMR you can get a similar amount of .22 WMR and some change or even a box of budget .223 Remington (which is a centerfire cartridge and is considerably more powerful).
While I appreciate the technology and R & D involved, I look at this as another one of those answers to questions nobody asked. Most people shoot rimfire, .22 lr mostly, because they are cheap, accurate and powerful enough to take small game. With price differences of up to 500% I can never imagine spending a lot of money on a rifle and ammo which in the end is just a glorified rat rifle.