Updated 13 January 2009

Polishing the 6" (15.2 cm) guns on a battleship
Caption reads "Showing a gunner's mate at his duties"
This may be USS Ohio B-12
U.S. Naval Historical Center Photograph # NH 101470

6"/50 (15.2 cm) gun aboard USS San Diego (ex-USS California) ACR-6 circa 1916
Note telescopic sight and the projectile at lower right
U.S. Naval Historical Center Photograph # NH 82997

U.S. Navy Armed Guard 6" (15.2 cm) guncrew on S.S. Mongolia in 1917
Officers are identified as Lieutenant Ware and Captain Emory Rice of the U.S. Naval Reserve Force
Note that the shells are painted "TEXAS" and "TEDDY"
U.S. Naval Historical Center Photograph # NH 781

This guncrew fired the first USN warshots of World War I when they engaged the German submarine U.B.40 on 19 April 1917.  The action is described on page 439 of "Home Waters Part VIII" as follows: "U.B.40 then went back to the Owers area, and on April 19, at 5.24 a.m., her periscope was seen in 50° 30' N., 0° 32' W., close to the American S.S. Mongolia (15,638 tons), New York to London, which opened fire with her 6-in. guns at 1,000 yards, and drove her down."  U.B.40 appears to have suffered little if any damage during this action and survived until 5 October 1918 when she was scuttled off Ostende during the German retreat from Belgium.

S.S. Mongolia was officially taken over by the Navy in April 1918 and then commissioned as USS Mongolia ID-1615.

Stern 6" (15.2 cm) gun on S.S. Mongolia in May 1917
U.S. Naval Historical Center Photograph # NH 41710

Another 6"/50 (15.2 cm) gun on S.S. Mongolia.  Mongolia carried a total of three 6" (15.2 cm) guns.
U.S. Naval Historical Center Photograph # NH 41973

6" (15.2 cm) gun on USS Pocahontas ID-3044 during World War I
Arrow is on the original and indicates the breech mechanism operator
U.S. Naval Historical Center Photograph # NH 82976

6" (15.2 cm) gun on USS Leviathan ID # 1326
U.S. Naval Historical Center Photograph # NH 2422

6"/50 (15.2 cm) gun on USS Maryland ACR-8
Note projectiles at lower right
U.S. Naval Historical Center Photograph # NH 73129

6" (15.2 cm) Common projectiles aboard USS Maryland ACR-8
The projectile at the lower left appears to be a dummy training round
U.S. Naval Historical Center Photograph # NH 73130

Bethlehem Steel 6"/50 (15.2 cm) gun No. 577 Model 1912 used on Argentine Battleship Rivadavia
Mounting now on display at Museo Naval de la Nación, Buenos Aires, Argentina
Photograph copyrighted by Carlos Mey and used here by his kind permission

15 August 2008 - Benchmark
13 January 2009 - Added two pictures of USS Maryland ACR-8