The Mark 15 torpedo was equipped. The 5 inch guns were removed some time after the torpedo tubes were removed in most cases. The as-built light AA armament of four .50 caliber machine guns (12.7 mm), the same as previous 1500-ton classes, was inadequate. This was partially remedied by increasing the number of guns to eight by 1941. As with most US Navy warships, the light AA armament was replaced with 40 mm Bofors and 20 mm Oerlikon guns within 18 months after the attack on Pearl Harbor. Initially, this was four 40 mm in two twin mounts and four single 20 mm guns. In 1945, with the emerging kamikaze threat and the dwindling threat from Japanese surface ships, Mustin, Morris, and Russell had all torpedo tubes removed in favor of four additional 40 mm guns for a total of eight in four twin mounts and were authorized replacement of the 20 mm single mounts by twin mounts; the latter part was not completed. The as-built anti-submarine armament of two depth charge racks was augmented by up to six K-gun depth charge throwers during the war. Service The class served extensively in World War II, and five of the class were lost in the war. Of the five ships lost, four were at the hands of the Japanese and one at the hands of the Germans. The class served on Neutrality Patrols in the North Atlantic, Caribbean, and South Atlantic in 1940–41. Except for Roe, Wainwright, and Buck, the class was transferred to the Pacific shortly after the attack on Pearl Harbor, where they often screened aircraft carriers. Two were sunk as a direct result of this duty by the same torpedo spreads that killed their carriers; Hammann escorting in the Battle of Midway and O'Brien escorting on 15 September 1942 (O'Brien did not sink until 19 October). In the Atlantic, Wainwright escorted the ill-fated convoy PQ 17, and with Roe supported Operation Torch, the invasion of North Africa. Buck'', damaged in a collision, missed Torch but was sunk by a U-boat off Salerno, Italy in 1943. The remainder of the class saw hard service in the Pacific. At the war's end in August 1945, three of the seven survivors were undergoing overhauls that were left unfinished, and were ultimately scrapped. The remaining four seaworthy ships were used as targets during the 1946 Operation Crossroads atomic tests at Bikini Atoll.