Why dont we make the minumum age at 30
Don't forget Uncle Sam gives them M-16s to carry, and gives them pistols to carry.
If the argument is maturity at 18, then maybe it should be moved to 21 for everything.
However, if it is considered that they are mature enough to join the army (during which they would carry of course), marry, etc.... then I say they are legally adults and should be able to carry.
Personally, at age 18, I'm not sure I would have said I was mature enough to do any of those. So I almost say move the age up for the others to 21.