Along the same lines of this question (if you don't mind me hijacking it), did anyone ever make a .22 Jet Improved? The .22 Jet flopped partially because it was designed as a revolver cartridge and had so many problems there. Out of a single-shot pistol or rifle, or out of even a good bolt or lever action rifle, it would be fun to play with and an improved version of it might be able to creep toward .22 Hornet out of a short (10" - 14") barrel.