Here, in Britain, the government is proposing a new bill to make fake, replica and bb guns illegal. It's because the number of fake weapons being used in robberied was up 50% from last year. I think there was also an incident when an armed police officer shot a car thief who had a bb gun. The officer (highly trained in the use of firearms) thought the weapon was real.
Also, the number of cats and dogs being shot with bb guns has increased and the RSPCA demanded that the weapons be made illegal.
Recntly, a cat got shot in the neck by a crossbow!! Thankfully it surived, but it does prove that computer violence influences people. (Or not).
PS: I will never, ever buy a bb gun. They are dangerous and morally wrong. (I hate guns a lot as I go to school in Aston, Birmingham, England, and quite a few people have been gunned down as part of a turf war).