Here's an interesting new cartridge. It is the 7.62x25 mm Tokarev necked down to .22.
It's called the .22 Reed Express and it will send a .22 caliber 50 grain bullet out of a pistol at about 2400 fps. The .22 Reed Express is intended for those large Czech VZ-52 pistols.
If you modify a VZ-52 this way, you have a poor man's 5.7x28mm.
Check it out at http://www.reedsammo.com
A .22 Reed Express would be a very interesting small game/ varmint round for a pistol. I just like the sound of the thing. And contacting Reed's Ammo for load data would likely be helpful in learning what powder to use in order to handload for the 5.7x28. That question came up about four weeks ago.