Age verification is just that it is verifying someone is over the age of 18. It is not gamer verification or maturity verification if it was either of those not too many around here would have the tag.
A, how do you know what I will do with that same gun? or anyone else that is already AV'd for that matter.
B, What I do is not your business or problem
and C, how is this about a 15 year old getting AV'd ? AV'd means 18+ OP is nearing 18 and wants to know if he will have to go to games to get AV the answer is no but it may be easier to get AV'd at a game you do not have to actual play to be verified of age.