I know you have filled in the "so what happened" part of this, but as someone who loves guns (the real type) and actually likes to go out range shooting, I still don't think it appropriate for kids to "play" guns. Kids seem to think that guns are toys, but in reality they are weapons and should be treated with respect. I know you can teach them real gun safety at 3 and 4 years old, and I would recommend doing that. I firmly believe that kids NEED to know how dangerous a gun really is because there are idiots out there. If that means taking that child to the range and having him see a watermelon the size of his head blow up when when it is hit with a bullet and then explaining that same bullet can do that to his head, DO IT. There are some great websites for this like http://www.corneredcat.com/ she is a woman that raised 5 boys and conceal carried a gun the whole time. And form some of her stories you can tell her kids were handfuls!