The W19, also called Katie, was an American Nuclear artillery shell, derived from the earlier W9 shell. The W19 is fired from a special 11 inch howitzer. It was introduced in 1955 and retired in 1963.
The W19 was 11 inches in diameter, 54 inches long, and weighed 600 pounds. It had a yield of 15-20 kilotons.
The W19, like its predecessor the W9, is a gun-type nuclear weapon.
The W19 nuclear system was adapted into a nuclear artillery shell for the US Navy 16 inch (406 mm) battleship guns, 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) diameter and 64 inches long (160 cm), with a weight given variously as 1,500 or 1,900 pounds in reference sources. As with the W19, yield was 15-20 kilotons.