After this photo was taken Battery Harris and its 16 inch gun was casemated.  The gun was test fired in the late 1930's and early 1940's so this picture is likely from then. These men are likely National Guard troops from the city, training to ward of the likes of German battle fleets. They manned two long range guns at Fort Tilden on the Rockaway peninsula and two more at Fort Hancock at Sandy Hook NJ. Both sites are now part of Gateway National Recreation Area.  For more, check out: http://www.oocities.org/fort_tilden/harris.html

Shells for  Battery Harris Fort Tilden NY 

American soldiers loading propaganda leaflets into smoke shells after the smoke candles have been removed & only gun powder is left so they can be shot across enemy lines at dusk for German soldiers to read, in the Cassino corridor of battle.Italy,February 1944.(rudeerude)

Artillery propaganda leaflets 

Infantrymen of the 2nd Division move up towards Krinkelt, Belgium. The orange circles painted on the back of their snow capes are for identification. January 31, 1945(rudeerude)