By the time the definitive B-17G appeared, the number of guns had been increased from seven to 13, the designs of the gun stations were finalized, and other adjustments were completed.
På det tidspunkt hvor den ultimative version, B-17G, fremkom, var antallet af maskingeværer steget fra syv til tretten, designet af skytternes pladser var færdigt, og en del andre justeringer var gjort færdige.