I discovered this shell while going through an old trunk recently. I was told it might have come from the USS Georgia during WWI.
I took some rough measurements: it is approx 20.5CM OAL and has a case length of 13.7 CM. It has a 4.5 CM diameter rim and is 4 CM in diameter above the rim. The projectile is approximately 4.7 CM in diameter. Can anyone ID this?