Only in one example were they used as secondary armament on a battleship, the Russian-built, repaired Iwami (ex-Orel) a prize of the Russo-Japanese War of 1904/05. In addition, the early Japanese aircraft carriers, such as the Kaga and the Akagi carried 8-inch guns. Both were built in 1920-25 were modernised between 1934 and 1938, but the guns were retained. Both were sunk in the Battle of Midway in early June 1942 (Jentschura et al. 1977, p. 42-44).
Argentinia had ordered the Buenos Aires (1895) with 2 single 8/45cal. guns (plus minor armament).Likewise, Chile had ordered similar vessels, namely the Esmeralda, the Blanco Encalada, and the Chacabuco, all with 2x 8/45cal. in single turrets, while the the General OHiggins carried 4 x 8/45 cal. in twin turrets (Jane 1990, p. 303).China had ordered the Hei Chi (1898) with a 2x 8/45cal. single turret configuration (Jane 1990, p. 310).
The total guns carried were: Kasuga: 1 x 10/45cal.; 2x 8/45cal.; 14x6/45 cal.; 10 x 12pdr.;2 Maxim guns. Nisshin: 4x 8/45cal.; 14x6/45 cal.; 10 x 12pdr.;2 Maxim guns (Jenstchura et al. 1977, p. 76-76; Jane 1990, p. 169).
Jentschura 1977, p.75-76.Other Armstrong-Pozzuoli guns, presumably from the same vessels, have been encountered as follows: 2x 6-inch on Fefan, Chuuk, reported to be from the Kasuga. (Denfeld 1979, p. 132); 2 x 6-inch Uman, Chuuk. manufactured in 1900 (Denfeld 1979, p. 132)
Jentschura et al. 1977, p. 73; Jane 1990, p. 169). Jane (1990, p. 169) asserts that the vessel carried 4 x 8/345cal. Armstrong guns in 1919.