Back on topic...
I've had guns drawn on me, twice, while taking photographs.

The first was near a large farm. I was on the road (not private property) setting up with a 4x5, to take a photo of a tree. While under the cloth, I heard yelling, so I turned to see an old man, with a shotgun, heading my way. A few seconds later, his son came running, yelling "Dad. Stop!" The son got the gun from his father, apologized to me, explaining that "Dad" had Alzheimer's, and they should probably lock up his guns. Good idea...

The other time was frightening. I was hired by a DC real estate management company to photograph some of the buildings they managed. Mostly office buildings, but there were a few embassies, too. For some of the embassies there were very specific rules. One was the Saudi Embassy. I could only photograph from the street, and it had to be done at a certain time of day. The company I was working for cleared everything with the embassy secretary, and I was set to go. I arrived at the appointed time, and began working. Within 3-4 minutes, about 6 guys, with guns out, were running at me, screaming (I can only assume it was abusive, as it was in Arabic). They grabbed my camera ( an SLR) and had me lay on the ground. A few minutes later, a few DC police cars arrived, as well as a handful of big black SUV's from the State Department. I explained to the cops, and State Department guys, what I was doing. At that point, the Secretary came out, apologizing because he'd forgotten to tell his security guys to expect me. I was allowed to finish, but 2 of the security guys followed me around.