The deferred deliveries of the P-40 were picked up again with the P-40B. In September 1940, 131 P-40Bs were procured by the Army to replace the deferred P-40s. The P-40B differed from the P-40 in having an extra 0.30-inch machine gun in each wing, bringing the total to four 0.30-inch guns in the wings. The two 0.50-inch guns in the fuselage were retained. The engine was still the V-1710-33. The first P-40B flew on March 13, 1941. The export equivalent of the P-40B was the Tomahawk IIA. They differed from the American version by having the wing guns replaced by four 0.303-inch Brownings. 110 were produced for the RAF. 23 of these planes were transferred to the USSR, and one went to Canada as an instructional airframe.