Warning shots are always controversial. I generally caution against them, but I keep finding instances where they are used to good effect. Here is one that was related on the opencarry.org North Carolina forum by tiggy1190. It occurred in Buncombe County, NC:
Forced to pull, and discharge outside of Asheville.
I wont go into all the details, but long story short. Drunk, and drugged up moron threatens me with a knife, then a gun, and advances towards me. I never saw the weapon, but his hands were behind his back the whole time. I knew I was just in taking a shot, but there were at least 30-50 onlookers standing behind him. I have a .40 Storm, and had 180g FMJ’s in it that day due to working in the woods around bears. I had an overwhelming fear of over penetration, so I gave a warning shot to the ground just in front of him. He retreated like a scalded cat. So far the BCSD has been extremely positive, and supportive through all this. They said I made the right choice. I feel the same. Sadly, some of my chest pounding family seems to think I should have shot him irregardless.
Just waiting on the SD to finish analyzing my weapon before they return it. All, but one officer that night supported me when the asked if I had a CCHP, and I stated “no, I OC”.