The verdict of Mantelli was not encouraging: the 'future bomber' "Leone" was not enough of an improvement to justify its replacing the CANT Z.1007, which was already in production for "Regia Aereonautica". A measure of the delays which this program suffered is given by the fact that, in spite of pressures caused by the war being waged at that time, it had taken six months to complete the proof-of-concept aircraft, and a true prototype would still have to be constructed in order to verify the adequacy of the basic design.