I have changed my Strategic Bombing rule.
A bomber bombing a factory for the first time recieves 1xd6 to damage enemy industrial complexes however, on a second raid when the same nation attacks the same enemy factory, all surviving bombers use 2xd6 and may choose the highest result rolled to inflict damage. During a third raid from the same nation against the same enemy factory, surviving bombers roll 3xd6 each and may choose the highest result rolled to inflict damage. Bombers receive 4xd6 each for the forth raid and 5xd6 each for the fifth (5 dice is the maximum each bomber may roll).
Each bomber may only apply 1 dice result to damage factories.
Each surviving bombers dice must be rolled separate from other surviving bombers dice.