Battleship U.S.S. Iowa contains three 16"/50 caliber Mark 7 guns. The turrets were called "three-gun" (rather than "triple") because each gun could be angled and fired independently of the others. These guns were 66 feet long and fired projectiles weighing anywhere from 1,900 to 2,700lbs at a max speed of 2,690 feet per second for up to 24 miles.
This world class battleship currently sits in the Suisun Bay Reserve Fleet awaiting her fate. Currently there is a batte between Long Beach and Mare Island as to where the ship will be docked and turned into a museum. The Navy seems to have chosen Mare Island as the ship's home, but San Pedro seems to have more funding and monetary support.