Following commissioning in the 9th Naval District, Magnet steamed down the Mississippi River en route to Norfolk, Virginia, reporting 17 April 1944.

After shakedown in the Chesapeake Bay, she joined Mine Division 31 and, for the next 9 months operated out of Recife, Brazil, sweeping the main shipping channels of South American ports.

On 10 March 1945 she was detached from the South Atlantic Forces and assigned to task group TG 23.2 at Miami, Florida.

Transferred to the Nationalist Chinese Government under the terms of lend lease the same day, she commissioned in that Navy as Yung Ning.

The vessel was officially returned in accordance with the terms of the original loan, and then redelivered to the Republic of China under the Military Assistance Program, 7 February 1948.