Just a couple years back, as I recall, an older gent received a Garand from the CMP.
He was a Korean War veteran.
Under the buttplate of his "new" Garand was the slip of paper that HE had placed there while standing on the banks of the Yalu River, which separates Korea from Red China!
That's one rifle about which we do know at least a partial service history.
Imagine the odds against THAT rifle returning to the hands that carried it in Korea....astronomical, to say the least.