I second the .22 or 9mm. For fun on range, .22 is actually quite fun especially when you get your fundamentals straightened out and can actually group shots.
9mm would be second choice, for it's ammo price, recoil, and again better to learn basics on. Also, same as .22, it's a lot of fun to shoot wen you can start to group with 9mm.
*edit* Would you buy a 450+hp car as first car or something more modest to learn the basics and gather some experience before moving to more powerful cars? I know it's not the best analogy, but close enough.
Let's wait until we actually see concrete legislation before we go off half-cocked. ~ Tom Servo