“People under the age of 18 are allowed to use firearms in every state I know of. “
By law, in every state, somebody under 18 must be under supervision of an adult to be in possession of a firearm.
He is also not able to purchase one.
There are exceptions.
That was an initiative pushed for by the Clinton Administration, about 1996, as I recall.
It might have been linked to federal funds.
Some states it is more enforced than others.
Not enforced in Alaska, as I understand it.
Not true for New Hampshire, except for pistols.