After the SB bombers were launched into full-scale production, their manufacturing technique, assembly quality, and operational reliability continued to be improved. The designers hoped to make the aircraft's flight characteristics better by installing more powerful engines.
In late 1936, full-scale production was started for the SB 2M-100A, which was equipped with the 860 hp Klimov M-100A twelve-cylinder, V-shaped, liquid-cooled engine and the VISh-2 three-bladed, controllable-pitch propeller. The shape of the nacelles was changed to an oval shape, instead of round nacelles like the previous version. The new engines improved the bomber's basic flight characteristics: maximum horizontal speed and rate of climb.
Based on the SB's tactical deployment experience in Spain, the bomber's armament was improved. The SB now featured an upper shielded Mozharovsky-Venevidov MV-3 turret with a 7.62 mm ShKAS machine gun. The turret had good visibility and increased firing angles. The turret also had a transparent cap (screen) whose upper section was fitted with aerodynamic trim, facilitating its in-flight rotation. The LU hatch mount was replaced with a retractable MV-2 mount, with the same ShKAS machine gun. A special feature of the MV-2 was a periscope optical sight. A rear-view mirror was also installed in the protruding transparent fairing over the pilot's cockpit windshield.
Up to 1940, only some production machines were built with MV-3 and MV-2 turrets. Mass conversion of the SBs to the new turrets was started only after the war with Finland.
In 1938, the production planes started to include self-sealing fuel tanks, but the protective cover, made of self-sealing sponge rubber, protected the tanks only from rifle-calibre bullet hits.
Two aircraft of the SB 2M-100A "Cruiser" variant were built. These machines had four quick-firing 20 mm Shpitalny-Vladimirov ShVAK aircraft cannons mounted below the forward fuselage.
Six production SB 2M-100As were equipped with launchers for six RS-132 rocket missiles under the wing panels. These planes participated in the Soviet-Finnish war.