Yes I have had 4 different times where having a gun has stopped an aggressive person from robbing me. As a Photojournalist I carry lots of expensive gear. It is my job tools,
After one football game, halftime, I headed out, got my shots to go back to the office. These two dudes followed me through the parking lot. At the time I carried a S&W 4516 (small 45). I stopped, turned around with gun in hand and like jackrabbits they went in different directions.
My girlfriend and I were at a rest stop reading a map when three hillbilly types got out of their old red truck. They started to fill water jugs. This was way out in no mans land, we could not start my VW van without a good roll downhill. They started mouthing off what they were going to do to my girlfriend, so all three started walking over to our car. I stepped ou of the van with my S&W Model 19 at my side... they scrambled back to their truck. I was thinking they were going for their shotguns, but they jumped in the old truck cursing a blue streek and took off. We opened both doors so the wind caught the doors like a sail and we were off.
Same van, we were parked behind a gas station in Baton Rouge FL late one night. Some idiot was trying to open the drivers wing window, he had his hand in the window when I laid the barrel of the S&W M19 on his arm... wow did he run fast.
The last time was this big black bear stold my food bag and came back for me. I had my Model 65 357 mag with me, well we both lived.
Over seas I had two other encounters but I was unarmed. Still lived.
In the states I have learned to never touch your defensive ammo when loading up, both revolvers and auto loaders. Never forgot that lesson.