A gun cannot be bad or good. You see, it's all about the intentions that those guns are used for. It I were to pick up a hockey stick and start attacking people with it. Would that render the hockey stick 'bad'? Therefor, he who is using the gun and how they are using it, is what the gun in turn is.
Guns are objects made by humans to do certain things, just like blades and swords etc. They all serve a purpose. You cannot categorize them as bad or good.