 The second version was a light night bomber (designated NBB - "nochnoy blizhniy bombardirovshchik" - Short Range Night Bomber), capable of carrying up to 500 kg of bombs on racks under the wing centre sections and with a defensive armament of a single ShKAS machine gun in a dorsal mounting.A total of 381 examples were built with production ending in 1943.A few examples of an improved version of the Yak-6 with swept outer wings were flown, with the modified version sometimes known as the Yak-6M.