There's another(bigger) shot analysis here.
http://www.targetshooting.ca/docs/Pi...t_Analysis.pdf
If you can keep 'em mostly in the black at 15 feet, you're fine though. Even the odd torso shot that goes to the '12/F1/F2' area will hurt. With a 3rd button on the shirt hold, one's liver is under the '12/F1/F2' area.