Well obviously what he needs is a better way to transport his weapons!
In Oregon minors may not "possess" guns. 18 for longguns and 21 for handguns is the law. There are exceptions for when used with the supervision of a qualified adult.
I was thinking a nice canvas bag he could unroll to reveal custom pockets for specific guns and ammo. Something he could pack in a hurry and wear with a shoulder strap.
Oh, wait. That's what I want.