Sorry to sound like a broken record, but even at around 600 to 650 fps the wadcutter will blow through more than 12" of 20% ballistic gelatin. See links above for proof.
Keep in mind the 20% ballistic gel test mix meaning that you cannot compare that with the standard 10% calibrated gel test mix. Also, that was bare gelatin. Add clothing and there are penetration concerns with a bullet moving at 600 fps. Not saying it won't kill someone, of course.