40 MM brass and projectile

WWII antiaircraft round. was widely on navy ships to shoot down Japanese.All shipsad many of these guns usually in sets. Very efective because of the rapid fire capability..
This projectile has never been fired, no marks on the copper band. Brass casing indicates it has been fired. Both kave beed demilitarized.
In the battle of Pearl Harbor some of the gunners on the ships shooting at low flyong Japanese aircraft inadvertantly fired into homes across the Bay..