In relation to the .17 HMR, a bloke in Australia named Arthur Langsford came out with a line of .17 rimfires in about the early 1970s. At least one, the .17 Tini-Mite, was available commercially from his shop. The .17 Tini-Mite used a .22 shot case (a bit longer than .22 LR) necked down to .17, and a 20 gn bullet was loaded to 3000 fps. There was also a .17 Vixen, on a .22 Mag case, and a .17 Minor Mite on the .22 LR case.
Back in the 70s .17-calibres were popular here, because the price of fox skins for the fur trade was so high - as long as they didn't have big holes in them. Blokes were going out spotlighting and making a fortune at it.
Unfortunately Langsford apparently had difficulties getting a reliable supply of primed cases, and couldn't get the momentum going on this one. As I think JB said earlier in this thread, you need to be able to hit the market with good supply, well distributed, of both rifles and ammo, to give something like this a good chance of lasting success.
