The NA-16-2K model was the type selected for initial production. The design featured several detail and structural changes, such as provisions for the fitting of a pair of forward-firing guns instead of the NA-16's single gun, and the strengthening of the tail and wings to better facilitate dive-bombing operations. Other modifications included the adoption of a single gun set on a swivelling mount to the rear of the cockpit, along with the installation of cameras and radio sets. On 27 March 1939, the first CA-1 Wirraway, RAAF serial A20-3, performed its maiden flight. This aircraft was subsequently retained by CAC for evaluation and trials for a number of months; on 10 July 1939, the first pair of Wirraways to be delivered to the RAAF, serials A20-4 and A20-5, were received by the service.