well I do have what are referred to as "hot loads" H-110 half a grain under max
I bet with a regular hard cast lead bullet, they would penetrate a best far better than a FMJ out of a 9mm.
An effective load for what Mel Gibson was referring to would probably be a sabot, like a skinny .177-.22 cal *steel* bullet riding in a plastic case.
the thing is a .357 mag is borderline able to penetrate a soft vest, it's effectively the same diameter as a 9mm luger (~.355), but with nearly twice the power.
So calling a 9mm a cop killer is kinda silly considering an "average" 357 is the limit of a soft vest.