I personally have shot multiple people with a pepper ball gun. For you folks that don't know, pepper balls are harder than your common paint balls, and they fire with more force. Some folks it works on, others it doesn't. In my 15 years of LEO experience, I prefer the pepper ball over the pepper spray. The physical impact of the pepper ball combined with the immediate dust of powder seems to have more of an effect. With that said, I have personally witnessed on multiple occasions where spray or pepper balls had little to no effect on a subject.
Do they work good to stop a bad person?
Not long ago, I responded to a fight with weapons included, 4 on 1. The victim was stabbed 37 times, with 3 shanks, and the 4th subject had a lock on a belt beating away on the victims head and face. Backup came into my unit from 2 directions, firing cans of gas, pepper spray, and shooting the main subject stabbing the victim with the pepper ball guns.The pepper balls were "walked in" from a distance up to point blank because he wouldn't stop. This man was literally straddling the victim, beating a 13" shank through this victims chest. The shank was literally exiting the back of the victim. When everyone was restrained, there were 7 pepper balls embedded in the subjects back, that had not burst. They were fired from such close range, they literally looked like giant cysts. In the debrief, the main subject stated "I never felt the pepper balls until after I was cuffed."
With that said, the pepper ball is just another tool. Like a taser, baton, pepper spray, etc they are not going to work 100% of the time on everyone. I personally am thankful our institutions have pepper balls, because walk a beat in my shoes
without a baton or side arm, you would be dam thankful for whatever munitions you are allowed to use.