seems an awful lot like the .218 Bee to me, and that might be a better case to work from depending on what your looking for. I dont really think it would serve any practical purpose that other rounds dont already fill, but hell if only practical mattered we wouldnt have so many cool rounds to play with.
What sort of rifle ( i assume its for a rifle) are you going to be using it for? I think it might make a really neat little project in the right gun.