Help identify this empty rifle cartridge

[Kokopelli]

Can you photograph it in your hand so that we can estimate it's size?

[nickel plate]

Can you photograph it in your hand so that we can estimate it's size?

15/32" x 1-13/16", just a little smaller than yours.

[joepamjohn]

Good thing you found it before 1/1/18 or you would need to get a background check before picking it up.