The Wildcat mentioned also had some pilots successful run it with 4x.50 (they dropped 1 in each wing) to get more aerobatic. They consider this successful a the time for the targets they were fighting.
The original F4F-3 had only 4 x .50 cals with a lot more ammunition per gun than the F4F-4. The change in armament was to suit the British. The GM produced FM version of the F4F-4 reverted back to the 4 x .50 cals of the earlier planes.
- Ivan.