A 22 will do it. In one ear and out the other.
How close does one have to be to achieve a pass-through, Scott?
It should wort to say 20 yards or so.
In reality it is somewhat surprising what a little bullet will do in just the right place. Through the spine just in front of the shoulder, in one ear and out the other. I have always felt bullet placement is far more important than a one pound bullet at 6,000 FPS.