Who on earth would use mini-grenades for close combat?
Oh... a troll. Gotcha.
Actually, the problem with A rounds is that they're heavier, carrying more kinetic force. So when it enters the body, it impacts bones and stff without changing direction (as your normal 9mm or 357 round does.) So in effect, it is a "stronger" hit.
Since it's designed to be used against cars, it's meant to punch holes in vehicle armor, and damage the people inside or the vehicle engine. (Or in really cool cases, the fuel storage!! MUAHAHAHAH BOOM!!!)
-Kid Vid