Bequests in a will are exempt from the usual interstate transfer regulations stipulated in Sec. 922:
Originally Posted by U.S.C. Sec. 922 (3)
(3) for any person, other than a licensed importer, licensed manufacturer, licensed dealer, or licensed collector to transport into or receive in the State where he resides (or if the person is a corporation or other business entity, the State where it maintains a place of business) any firearm purchased or otherwise obtained by such person outside that State, except that this paragraph (A) shall not preclude any person who lawfully acquires a firearm by bequest or intestate succession in a State other than his State of residence from transporting the firearm into or receiving it in that State, if it is lawful for such person to purchase or possess such firearm in that State,
I'd make sure I had a notarized copy of the document. If I really valued the guns, I might go ahead and do an FFL transfer anyway, just to make everything doubleplus legal.