Butler (DD 636).
In the summer of 1942, 40mm twin Bofors became available. By this time, some yards (e.g., Bath) had discontinued production of 1,630-tonners and were commencing production of the first Fletchers. Others, such as Sea-Tac and the four navy yards, changed over later while Federal continued to complete 1,630-tonners alongside the newer class, launching two ships of each class in a single day, 3 May 1942.

The availability of the new twin Bofors made possible side-by-side mounts in place of the ineffective 1.1-inch cannon and 20mm aft.

Of the ten-tube ships modified in early 1943, those serving in the Pacific, where surface action could be expected, retained both their torpedo mounts. Those serving in the Atlantic, where surface targets were not likely, tended to be reduced to five.