One more point you may want to add is this "The presence of a firearm detours criminals". They have done tons of documented interviews on prisoners to find out how they chose their victims or establishments to rob. They have found that a criminal most often will go in and case the place 1st. If someone with a firearm is there they will not take the risk and do 1 of 3 things. Try to wait till the armed person leaves, go look for another location to rob, or plan to come back another time. An exposed firearm is a very well documented crime deterrent.