All this talk reminds of the Wind River. Its hard to know what to do in situations like this. I think it pays to fish with a friend or group of friends.

Last spring, I had a similar situation, when there were 10 guys fishing next to each other(including me). Most anglers cast in order and were generally cordial. For whatever reason, some guy wanted my spot(maybe because he thought I was alone). He started above me only 5 feet or so, then proceeded to crowd me and my casts. Then he went around me crowded from that side. I turned around to rebait and he tried to get his buddy to take my spot. I didn't budge. Although I tried to start a conversation and be cordial, all that I got in return was snide comments about my casting. I had a friend about 30 ft away, but since I couldn't talk to him, this other guy thought I was alone. I do think if you stand your ground, more often than not, the instigator will back down. If not have a friend close by.

By the way, when guns are pulled, its time to leave, no matter what.