The Boeing YB-40 Flying Fortress was a modification of the United States B-17 Flying Fortress bomber aircraft, converted to act as a heavily-armed escort for other bombers during World War II. At the time of its development, long-range fighter aircraft such as the P-51 Mustang were just entering quantity production, and thus were not yet available to accompany bombers all the way from England to Germany and back.
I think this would be a great touch to bomber mission??



Armament
Guns: 18 (or more) × .50 in (12.7 mm) Browning M2 machine guns. Typically used 14-16, with room for up to 30.[citation needed]
Location Rounds 
Nose 2200 
Front top turret 2500 
Aft top turret 3300 
Ball turret 300 
Waist guns 1200 
Tail guns 1200 
Total 10,700 
<info and pictures from Wikipedia>