*Disclaimer* *I have absolutely no experience or facts to back up the following, it is just my opinion.*
IMHO Put a cast iron frying pan against your chest and have a buddy hit it as hard as he can with a baseball bat and that will be similar to being hit with a high power pistol round with armor (probably a bit more but close enough for this example). This will stun any BG enough to get him to stop shooting and give you time to try for a head shot. Anyone on PCP ... well I doubt they will be using a firearm or using it accurately if they are. If you are up against a combat vet on psychiatric drugs .... well you are probably out matched & *******ed anyway.
Just my opinion.