Updated 15 June 2010

USS Memphis CL-13 about 1941-42
The cylinders atop the mount supply water and compressed air
Note the 3"/50 (7.62 cm) AA gun behind the turret
Detail from U.S. Naval Historical Center Photograph # 80-G-10535

Two of the casemate guns on USS Omaha CL-4
Picture taken in August 1933 after overhaul at the Puget Sound Navy Yard
Note the rangefinder and the Battle Efficiency "E"
Detail from U.S. Naval Historical Center Photograph # 93507

After twin mounting on USS Marblehead CL-12 during repairs at New York Navy Yard in 1942
U.S. Naval Historical Center Photograph # 80-G-254938

USS Narwhal SS-167 in 1943
One of the "submarine cruisers" with two 6"/53 (15.2 cm) guns
Note the open breech on the aft gun

USS V-4 (later Argonaut SS-166, later APS-1) in June 1928
Note the ammunition scuttle at left and the bipod barrel support in the foreground
Detail from U.S. Naval Historical Center Photograph # 69206

6"/53 (15.2 cm) gun on USS Argonaut APS-1 in August 1942
Note the pinion and arc elevation gear
Detail from U.S. Naval Historical Center Photograph # 80-G-11741

SP Common Mark 27

Cutaway view of SP Common Mark 27

20 June 2007 - Benchmark
15 June 2010 - Added picture and cutaway of SP Common Mark 27 projectile