Unfortunately, almost all commentators go off on the will-it/won’t-it question of performance against armor. I don’t think that’s the important question.
While ss190 is interesting its ability to defeat body armor from a pistol, I’m more interested in terminal ballistics. Leaving aside armor penetration, the ss190 is ballistic ally equivalent to ss192, 195, and 198 against unarmored targets. All three of those loads are available to lesser and greater degrees, for quite reasonable prices. All three chrono at just under or just over the magic 2000 fps mark.
So the question remains, what kind of efficacy can a civilian expect when using the non-sporting rounds for self defense?
I can't honestly answer that one. Like a lot of light, fast rounds, it tumbles and fragments, making consistent performance in tissue difficult to predict. Some folks insist it's no better than a .22 magnum, others point out that Major Hassan managed to kill 13 people with one. Those operators who do carry it like the 20-round magazine capacity and the super-fast shot recovery to target. I don't think it would be my first choice just due to size, (I'm not real big and it's a little hard to conceal) but I sure wouldn't want to get hit by one.