The shooter of the upper defensive machine-gun turret of the Soviet TB-3 bomber is a 7.62-mm DA aircraft machine gun (Degtyarev Aviation).
Ahead is TB-3 bomber wing and an M-17 engine.
In the background are two Soviet Il-4 (DB-3F) bombers of the Red Army Air Force.
The author’s name of the TB-3 photo is “Bombers are flying to carry out a combat mission”.