A 1944-dated US Navy 20x110RB Oerlikon Drill Cannon Round with traces of the original brown paint on the projectile.
The headstamp is "B (in a diamond shape) 1944 20MM MK4"
I think the manufacturer is Bridgeport Brass Coy., Bridgeport, CT.
The dummy fuze is stamped: "M -26-1-DOCCO-T"
The 20x110RB was the standard light anti-aircraft round for the US and British Navies in WWII.
Sorry, no international shipping.