The design was now intended to meet a 1936 specification for a long-range fighter, competing with the Potez 670 and the SNCASE SE.100. The H.220-2 was exhibited at the 1939 Brussels Air Show to represent the NC-600, but the real NC-600 was a further redesigned aircraft, with new wings and revised tail surfaces, and was now being offered as a two-seat aircraft. The proposed armament was also revised, with two additional fixed forward firing machine guns and the two rear-firing guns replaced by a single flexibly mounted cannon. The NC-600 prototype flew on 15 May 1940, but again other types were preferred, with orders being placed for 40 Potez 671s and at least 300 SE.100s. Work on the six-aircraft evaluation batch was stopped by the German occupation of SNCAC's Bourges factory.