The FReeper Foxhole Remembers the Battle of Rennell Island (1/29-30/1943) - June 9th, 2005

World War II Magazine | March 2000 | John Wukovits

[Iris7]

The guns were 5 inch 38 calibers.

Notice that the ship carried a lot of ammunition. Ammunition is loaded on the ship by hand, each projectile and powder case carried by one man, up the gang plank, through the ship, and down to the magazine. Then went back for more. A tiring job.

[PAR35]

The guns were 5 inch 38 calibers.

Perhaps the 5 inch guns were replaced at some point. (I had speculated upthread that the number may have been doubled as was the case with her sister ship.) In any event, the 5"/25 caliber came from the link you provided. "armed with nine eight-inch .55 caliber guns; four 5-inch .25 caliber guns; eight .50 caliber machine guns; and six 21-inch surfaced torpedo tubes." http://www.pirtle.org/chicago.htm

I will note that the 5"/25 was a standard gun when the ship was built, and it predates the 5"/38. Here's a writeup on the gun: "This was the first USN heavy AA gun designed for the purpose and was used on most USA capital ships and cruisers built or modernized between 1926 and 1940." http://www.navweaps.com/Weapons/WNUS_5-25_mk10.htm
and here is the index page for naval guns: http://www.navweaps.com/Weapons/WNUS_main.htm

The 5"/38 was not available until 1934, and thus would not have been put on the ship when it was built in 1929-30.