Are If you are speaking specifically of the SS190 round (which I believe is the AP version of the round), then it is strictly forbidden in the civilian market for being too capable (as you pointed out).The Youth Counselor said:Don't take my word for it. I never fired a Five-SeveN, but from what I read a 5.7 round actually has very good stopping power, although different sources have different testimonials. Especially in the case of it's innovative SS190 ammunition, it is bottle nosed and tipped, almost a scaled down 5.56 round. Because of the velocity and shape, it may penetrate dozens of layers of armor but will never overpenetrate. That is because it is weighed down in the core (With a metal ball, FYI making it a literal ball round.) When impact occurs the core shifts out of place, destabilizing the bullet and making it tumble downwards instead of passing through the mark. Thus it dumps possibly all it's kenetic energy into there, and provides the best of five worlds. It's has negligible recoil, armor penetrating capabilities, good stopping power, and abides by the Geneva convention for use in warfare.
However, the SS197SR and the hollow points (designation unknown) don't have quite the same characteristics as I do not believe they are built the same way. The SS197SR that I happen to have right in front of me is loaded with a Hornady 40gr. V-Max ballistic tip, so its penetration will probably be less, and it will probably tumble more since the polymer tip seems to be designed to crumple/deform on impact while still keeping the aerodynamics of the round in tact during 'flight.'
I have heard of people loading .223 bullets into spent 5.7x28mm cases, but not only will that void the warranty of a possibly $1000+ handgun, but it can also cause the round to EXPLODE! It's kinda like how people don't usually reload .44 rounds because they are so pressure sensitive.

I should point out that this particular model of Five-Seven is no longer in production (IOM model), and the USG model is far more reliable.