The most vehemently anti-gun liberal at the old job was exactly what Monkeyleg described. Very bad temper when things didn't go his way and I once heard him say, " I hate guns, but I wish I had one right now so I could shoot this place up." The rest of the time he would talk about the stupid redneck gun owners and their violent ways.
You know, in general, I despise those stupid HR policies and workplace violence presentations that say things like "if you hear someone talking about guns or violence, it should be reported as a possible indication of a problem," but whenever someone, especially an anti gun type, expresses the desire to "shoot this place up" outside the context of a security training exercise, I'll be the first in line to report it to my supervisor, their supervisor, HR, the highest official of the company I can get my hands on quickly, the police and probably my attorney just in case, so that if anything happens to me as a result of HR failing to take swift, decisive and effective action, my kids might get more from the lawsuit that will follow.