I think ScottsGT has got it, more or less... they'd be "returning" it. I'm not the smoothest lawyer or the most knowledgeable gun afficianado on the board, but it dosen't sound right that you could ever bring back your issue weapon as a "war trophy". The relatives would be discovering that they are inadvertently in posession of USMC property, and in returning it, probably neatly sidestep the Feds. If the family gets on the horn to the USMC museum and signs some paper quickly, there's just no reason for a squabble. DOJ dosen't pay it's attorneys to fight Marine and Navy JAG's over museum donations. What would congress say about those legal bills?