17hmr. The guy in CO was not wearing body armor he had a ballistic vest big diff. 500smith will knock the chocolate out of ya and break some ribs but so will a 44 mag 357 mag 45 acp many others. If you want to penetrate body armor you need 223/556nato and up. Many pistol versions out there for home defense. You can still pick up an SKS for a fairly good price. They are cheap and fun to shoot and will defeat most body armor.
The hips are extremely vascular as well as debilitating if struck. Its not a cns shot they are going to be able to shoot at you but they wont be able to chase you. It would be my 4th choice head/spine/heart&lungs/Hips/liver/femur/ etc e tc.