I recently talked to Clark Perks, development director at the Battleship New Jersey Museum and Memorial and he has an 888-foot battlewagon full of armament that includes nine massive 16-inch and 12 5-inch guns, but what they are missing is a complete 20mm Oerlikon cannon.
They have the gun itself, they just need the mount and shield and can work to fab one from an original if they could work out the loan…
More in my column at Guns.com
P.S. They just got their 40mm quad mount restored– and it even fires.