The W19, also called Katie, was an American nuclear artillery shell, derived from the earlier W9 shell. The W19 was fired from a special 11-inch (28 cm) howitzer. It was introduced in 1955 and retired in 1963.
The W19 was 11 inches (28 cm) in diameter, 54 inches (140 cm) long, and weighed 600 pounds (270 kg). It had a yield of 15-20
The W19 nuclear system was adapted into a nuclear artillery shell for the US Navy's 16-inch (406 mm) main battery found on the Iowa-class battleships, the W23. Production of the W23 began in 1956 and they were in service until 1962, with a total of 50 units being produced.
The W23 was 16 inches (406 mm) in diameter and 64 inches (160 cm) long, with a weight given variously as 1,500 or 1,900 pounds (680 or 860 kg) in reference sources. As with the W19, yield was 15-20 kilotons.