Originally Posted by RunningOnMT
Would the same principle apply to body armor ? In other words all other factors being equal, would a wad cutter bullet penetrate personal body armor better than pointed or round FMJ ?
No, for several reasons.
First, that principle uses kinetic energy transfer to spall the armor; that is, it fragments the other side into lethal fragments. (It is not a very efficient mechanism really, compared to others. The projectile does not really ever penetrate the armor. A penetrator actually does, and generates a great amount of heat, along with spall too, so it does much more damage with less effort and usually a larger effective range.) Soft body armor will not spall.
Second, the kinetic energy transferred by self-defense handguns, even .357 Mag, is not even close to being lethal or enough to stop a man. A boxer can punch nearly twice as hard as a .357 Mag will hit a vest.
Third, this principle does not use penetration, therefor it wouldn't defeat a vest.
Fourth, many modern armored vehicles defeat spall by having crew compartments lined with kevlar panels hardened by resin. That right there tells you busting a SAPI plate this way will only get the fragments stopped by the vest behind it anyway, which is easy to see how.
So no, it wouldn't be effective.