Besides the main dual-purpose guns, initial (April–May 1942) anti-aircraft armament was light; a quadruple 1.1"/75 caliber gun (located in an elevated tub between the number three and four 5"/38 caliber gun mounts), and six Oerlikon 20 mm cannons (two in front of and below the bridge, and four amidships). Beginning in June 1942, the 1.1" gun was replaced by a twin Bofors 40 mm gun mount, plus another twin mount on the fantail between the depth charge racks. In February 1943, the fantail-mounted Bofors was removed, and instead, one twin mount was placed on each side of the aft funnel, bringing the total number of 40 mm barrels to six. In 1942 and 1943, the number of Oerlikon cannons was steadily increased. Ships were often modified before leaving the shipyard with a seventh 20 mm mount in front of the bridge behind the number two 5"/38 caliber gun mount, and anywhere from one to three mounts on the flying bridge depending upon the bridge configuration of the ship. In combat, commanders often requisitioned additional guns, and some Fletchers mounted up to thirteen 20 mm cannons. In June and July 1943, two more twin Bofors mounts were added in place of the 20 mm cannons in front of and below the bridge, giving a total of ten barrels. With this modification, the Oerlikon cannons were rearranged and their number was standardized at seven; four amidships and three in a heart-shaped mount on the fantail.