From around June or July of 1951 through January 1961, the 325 was involved with the Dew Line. This was the Early Warning Radar set up by the Air Force to keep tabs on Russia during the "cold war" all along the American and Canadian borders.
With but a few Navy personnel assigned to operate the 325 while the rest of the crew were mostly Merchant Marine, the 325 was taken out of moth balls in Florida. The guns were removed when mothballed.
Figuring there was no need for armed protection during this time period, none were replaced at that time.
There was a bit of excitement in 1951, not related to guns, the 325 was badly damaged by an iceberg (port aft) and had to return to New York for repairs. The area in question is very visable today.
They also had engine problems (starboard, as usual) and it limped into New York for repairs to both the skin and engine.
The original tubs standing empty today were still on board as they are today.