There are also various handgun rounds out there that will zip through III no problem.There are rifle rounds available to the public that will penetrate Type III armor.
On a separate note, 5.7mm sucks, and here's my logic for that. It's a submachine round. In something like a P90, it's a wonder. More controllable than a 9mm sub and more penetration. That is what the round is made for. However, us plebs currently can't have actually sub guns, which means, it ends up sucking. In a pistol, it's comparable to most other rounds. In a larger platform (without select fire) there are other, better options. A light AR pistol will have far more punch than a P90. And without full auto-and controllability thrown into the mix, it's a cheaper better option.
Don't get me wrong, I think the 5.7 is a fabulous round, but really only in a full-auto subgun, like it's designed for. Anything else and there are better options.