I told the boys if they can play this game and not shoot their eyes out then they will be old enough for a BB gun http://www.dontshootyoureyeout.com/
That's what goggles are for! We used to run around shooting each other with ski jackets and goggles. Not that I want to date myself - but clearly this was pre-paintball.
They wanted paintball guns and that was a no way ..So, I got them both camo colored BB guns with a scope and pump action..We will be camping out in the desert on Christmas so they will have open spaces to shoot I did tell them that if they aim any gun at anyone, that I will be the proud owner of the BB gun and they will not get them back until they are older..