What's the difference between a toy gun and a Nerf Gun or a Water Pistol? Just a question
You think kids don't run around with Nerf guns shooting bullets and say "you're dead"?
I look at water pistols and nerf guns as a compromise. I don't think I'll be able to shield DS from toy guns completely, and as a PP mentioned, you can make guns out of lego or a stick. If he were to ask for a water pistol or nerf gun, we would allow it on the proviso that the aim is to have water play with the water guns, or getting each other with the nerf guns. With realistic looking toy guns the only aim is to kill each other, or shoot each other.
I'm probably not articulating myself very well, and I could well be being naive in thinking we'll be able to do it. I know he's going to go off to school and friend's houses and play games without us knowing, but if he asks for a toy gun at some point I'd like to explain to him why we don't want him playing gun games.