Without going through them all - it's mixed. The ones below legal age obviously are breaking the law.
The adults usually are legal purchases.
In some like Kip Kingle - the parents bought him the Glock but technically they owned it.
BTW - here's another pro-gun Senator:
http://www.politico.com/story/2012/1...348.html?hp=r2
Scott Brown - probably wants to replace Kerry, so setting himself up on the high moral ground.