Here's the part I find interesting....
Six fixed forward firing 0.5in Browning wing guns with 400 rounds per gun (some F6F-5 and F6F-5N Hellcats had two 20 mm cannon plus four 0.5 inch machine-guns)
Not just he 5N's had 20mm, F6F-5's were delivered to the fleet (both US and British) with factory installed 20mm toward the end of the war.
I have a book here that merely states something to the effect of "late model production runs" of the F6F-5 could carry the mixed armament, the airframe allowed for it. Use by the USN was very limited, I can only find mention of a couple -5N's that actually carried the armament into combat and no mention of any of the standard F6F-5's. Can't speak for the British.
