I confirm what's been said as to legality above, with one exception: you don't have to be eighteen to open carry as long as you're being directly supervised by a responsible adult. There is no minimum age to OWN a gun, but you have to be at least eighteen to be in POSSESSION of a gun except as noted. And, of course, you can't have been adjudicated insane, involuntarily committed, or voluntarily committed as a result of a temporary detention order, an illegal immigrant, a convicted felon, subject to a protective order, etc. "Openly carried" means carried in such a way that an interested observer who bothered to look would have seen the gun or enough of the gun to have a clear understanding of what's there. The alternative is "hidden from common observation". The intent to "hide" isn't required, the intent that's required is the intent to be in possession of the gun along with the fact that it isn't obvious to someone who's looking. "Possession" means on or about your person in such matter that you have the immediate power of dominion and control over the gun. And that's all I have to say about that.
