At least in my state (PA) I don’t know much about others but I assume that some are at least similar. As an 18 year old I can; openly carry a hand gun, as long as it’s always visible; I can own one, as long as it was won or gifted (the legal way this is still a process where I will need to go to a dealer with their FFL and get it transferred). But I’m not allowed to purchase one from a licensed dealer or any ammunition for it. It seems backwards to me but most people don’t know that there are legal ways for an 18 year old to own and carry a handgun (again at least in my state) and yes the second amendment doesn’t reference age but the whole constitution is applicable to any American citizen of at least 18 years old. And that’s every amendment. So as soon as age becomes a factor on any one amendment then the whole voting process should be raised along with that specific amendment.