I have on several occassions on the highways.. Both times no shots were fired.. once it was drawn the threat left... One was back in the 80's.. I was driving through a reservation. A van full of locals pulled up behind me in a van..I was in a Honda Accord.. they pulled beside me and tried to run me off the road.. I hit the brakes and they overshot me.. I passed them later at a high rate of speed.. again they pulled beside me however by then I had reached under my drivers seat and pulled out my Ruger Security Six in .357 Mag.. waived it the passenger who turned and said something to the driver.. they backed way off and let me alone..

Had an incident in a west coast city.. approached by 2 fine young men.. looking for free shit.. I opened my jacket as I stepped back so they could see my handgun..they decided to go elsewhere..

Another time some asshole wanted to run me off the highway while I was on my Harley with his Cadillac .. I reached under my jacket and grabbed a S&W 357 snubnosed revolver.. pointed directly at the driver.. he braked very hard... that ended that...

Not a handgun but firearm below..

As a farm kid I shot twice at vehicles coming into our yard trying to steal gas in the middle of the night.. they lost some tail lights one night when my brothers and I opened fire on them.. this was in the 70's..

One day we went home early to milk the cows as we were having my parents 25th wedding anniversary to attend... In broad daylight a pickup with a 50 gallon drum in the back pulls up to our gas pumps.. I had a 12 gauge in the barn to use on skunks and such that we might run into.. as they got out of the truck and in the box I let loose a 12 gauge round directly at them.. they were back in their truck in olympic times spinning the tires to get out of our yard..I fired 2 more at their vehicle leaving..

One summer evening I heard voices in my farm yard at 3AM.. I was on particularly high alert as 2 elderly people had just been killed in Minot ND.. brutal..with throats slit and shot in the head.. I had helped the local sheriffs look for them in abandoned farm yards and riding fields with my horse.. Anyway, I woke my wife and handed her my handgun by the bed.. grabbed an AR and went to the door..Sure enough they knocked..I hit a very bright light shinning to the outside.. told them to step back from the door.. I used my foot to open the door while keeping my AR on them.. THEY freaked out.. come to find out they were from the Air Force base in Minot.. were attending a street dance in the local town and had hit the ditch with their vehicle while on the muddy roads.. still didn't explain why they were 4 miles off of the highway which is where my farm was at the time.... I called my neighbor who come down and assisted in pulling them out.. I kept the AR in my hands the entire time..I imagine they had quite the story to tell once they got back to base..

These are the immediate ones that come to mind....